I roast a tray of sweet potatoes almost every Sunday and I never plan what happens to the last one.
It sits in a container on the top shelf getting colder and more forgotten by the day.
One Wednesday I gave up on reheating it and threw it in the blender with a frozen banana.
Forty five seconds later I had the best glass of anything I'd made that month.
Now I roast an extra potato on purpose.
My wife thinks it tastes like a milkshake that somehow got away with it, which is about right.
It's thick and cold and faintly spiced, and it goes down in about two minutes flat.
One thing to get clear before you start, because there are two very different recipes floating around under similar names.
This is a drink.
It pours from the blender into a tall glass and you drink it, no spoon involved anywhere.
If you want the thick kind you eat with a spoon and pile with granola, that's a smoothie bowl, and it's built differently.
This one is loose enough to move, thickened by frozen banana instead of ice so nothing gets watered down.
Five minutes from fridge to glass, and that's counting the washing up!
How to Prepare Sweet Potato for a Smoothie
Roast it whole, cool it completely, and scoop the flesh. That's the whole prep, and it's worth doing properly because it's the only part that takes any time.
Prick a few medium sweet potatoes and bake them at 400°F for 45 to 55 minutes, until they slump and a little dark syrup leaks out onto the tray.
That syrup is the sugar concentrating, which is exactly what you want.
- Roasted beats boiled. Boiling pushes water into the flesh and pulls flavor out. In a cold drink that reads as watery and bland.
- Canned puree works in a pinch. Plain puree, not pie filling. It's flatter, but it's a Tuesday, nobody's judging.
- It must be cold. Warm puree makes a lukewarm smoothie, which is genuinely unpleasant.
- Freeze it in portions. Half cup scoops in a bag. Then this is a two minute recipe forever.
No, Not Raw
People ask this constantly, so here's a straight answer: don't put raw sweet potato in a blender. It isn't dangerous in small amounts, it's just bad.
Raw sweet potato is dense, starchy and chalky.
A home blender can't break the cell walls down, so you get grit that settles at the bottom of the glass.
It's also hard on your stomach raw, which is not true of carrot, and that's where the confusion usually comes from.
Cook it, chill it, then blend it. There's no shortcut here worth taking.
What Goes In
- Roasted sweet potato (½ cup). Cold, scooped from the skin, no strings.
- Frozen banana (1 small). Peeled and broken up before freezing. This is the thickener and the sweetener in one.
- Greek yogurt (½ cup). Plain whole milk. Gives it body and a little tang against all that sweetness.
- Whole milk (⅔ cup). Adjust it up or down depending on how you like to drink it.
- Cinnamon (½ teaspoon) and cardamom (⅛ teaspoon). The cardamom is optional and it's the thing people can't identify and keep asking about.
- Vanilla (½ teaspoon). Rounds everything off.
- Salt (a pinch). Makes it taste like a real drink instead of a health project.
- Maple syrup (½ tablespoon). Only if you need it. Taste first.
Fair warning: don't reach for ice. Ice adds volume and takes flavor away, and frozen banana does the same job while adding something.
How to Blend It
Step 1: Load in Order
Milk goes in first, then the yogurt, the sweet potato, the spices and the vanilla, and the frozen banana pieces last on top.
Liquid at the bottom means the blade actually catches something instead of spinning against a frozen wall.
Step 2: Low to High
Start slow for five seconds, then run it on high for 45 seconds.
Stop once, scrape the sides down, and go again for another 15 seconds.
Step 3: The Pour Test
Tip the jug and watch it.
It should fall in a smooth unbroken stream and settle level in the glass within a couple of seconds.
If it plops out in one lump, it's a bowl, not a drink, and it needs more milk.
Thick or Thin, and How to Fix It
Drinkable is the target here. You should be able to drink it from the glass without tipping your head back.
- Too thick. Milk, two tablespoons at a time, blended for five seconds between each addition.
- Too thin. Half a frozen banana or another spoon of yogurt. Never ice.
- Grainy. The potato wasn't fully cooked. Blend longer, and roast it further next time.
- Want it thick enough to hold granola? Then you want a smoothie bowl, and you get there by cutting the milk roughly in half.
Substitutions
- No banana. Frozen mango chunks, or an extra quarter cup of yogurt plus a pitted date. Less sweet and slightly less creamy.
- Dairy free. Coconut yogurt and almond milk work. You lose some thickness, so hold back a splash of the milk.
- No cardamom. Pumpkin pie spice, or just more cinnamon.
- Pumpkin instead. Canned pumpkin puree swaps in directly, and it's a little more savory.
Additions
- Protein powder. One scoop of vanilla. Add two extra tablespoons of milk with it.
- Nut butter. A spoon of peanut or almond butter makes it a genuine meal.
- Rolled oats. Two tablespoons, blended in, for staying power.
- Orange juice. A quarter cup in place of some of the milk brightens the whole glass.
- Flax or chia. A teaspoon, blended, and drink it fairly quickly because chia thickens as it stands.
Make Ahead and Freezer Packs
This is where the recipe stops being a weekend thing. I keep four packs in the freezer at all times.
- Build the packs. Half a cup of roasted sweet potato, one broken up banana and the spices, all in one freezer bag.
- Blend from frozen. Tip a pack into the blender with the milk and yogurt. Two minutes, start to finish.
- Blended and stored. It keeps a day in the fridge, sealed, but it separates. Shake it hard before drinking.
- Don't freeze it blended. It comes back icy and grainy and there's no fixing it.
Worth roasting an extra potato for? I do it every week!
Recipe
Sweet Potato Smoothie
Ingredients
For the Smoothie
- ½ cup roasted sweet potato flesh cooled completely
- 1 small frozen banana peeled and broken into pieces
- ½ cup plain whole milk Greek yogurt
- ⅔ cup whole milk plus more to loosen
- ½ teaspoon ground cinnamon
- ⅛ teaspoon ground cardamom optional
- ½ teaspoon vanilla extract
- 1 pinch fine salt
- ½ tablespoon maple syrup only if needed
Instructions
Roast the Sweet Potato
- Prick a few medium sweet potatoes and bake at 400F for 45 to 55 minutes until they slump and leak a little dark syrup. Cool completely, then scoop out the flesh. Never use raw sweet potato in a blender.
- Measure ½ cup of the cold flesh for this smoothie and freeze the rest in ½ cup portions for future glasses.
Blend and Pour
- Pour the milk into the blender first, then add the yogurt, the cold sweet potato, the cinnamon, cardamom, vanilla and salt. Put the frozen banana pieces in last, on top.
- Start on low for 5 seconds, then blend on high for 45 seconds. Stop, scrape the sides down, and blend another 15 seconds.
- Check the pour: it should fall from the jug in a smooth unbroken stream and settle level in the glass. If it comes out in a lump, blend in more milk 2 tablespoons at a time.
- Taste, add the maple syrup only if it needs it, and pour into a tall glass. Drink it right away, no spoon needed.
Notes
- Never raw: raw sweet potato is starchy and chalky, a home blender leaves grit, and it is hard to digest. Cook it and chill it first.
- Roast, do not boil: boiling waterlogs the flesh and washes out flavor, and it shows in a cold drink.
- Frozen banana, not ice: ice adds volume and dilutes flavor. Frozen banana thickens and sweetens at the same time.
- This is a drink: it should pour in a smooth stream and settle level. For a spoonable version, halve the milk and make a smoothie bowl instead.
- Freezer packs: bag the sweet potato, banana and spices together, then blend with milk and yogurt for a two minute breakfast.
- Do not freeze it blended: it thaws icy and grainy.
