So simple, so delicious. Rainbow cubes are a great on-the-go treat to keep you going. Kids will love the color. All will love the taste. It's amazing such goodness can come straight from the ground. The purple variety can be found in Chinese/Japanese markets.
Serving: 2–3 cups (720 ml)
1 small Okinawa sweet potato (purple), peeled and cut into ½-inch cubes
1 small sweet potato (white), peeled and cut into ½-inch cubes
1 small yam, peeled and cut into ½-inch cubes
Extra-virgin olive oil
Kosher salt and freshly ground pepper to taste
- Preheat oven to 425 degrees. Place cubes in large mixing bowl and drizzle with oil. Toss to ensure even coverage. Salt and pepper generously.
- Spread cubes in one layer on baking sheet so they do not touch. Bake for approximately 30-35 minutes, flipping cubes half way through. Watch carefully to avoid burning. Once cubes are crispy on the outside and tender on the inside, remove from the oven and cool.
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Rainbow cubes are roasted sweet potato in three colors — purple Okinawa, white, and classic orange yam — tumbled together until crisp at the edges and creamy inside. The trio looks spectacular on the plate and tastes subtly different in every bite. Roasted hot at 425°F, they are the side dish that steals the meal.
Pro Tips
- Give every cube its own space on the pan. Crowded cubes steam and go soft; a single layer is what makes the edges shatter-crisp.
- Cut the three varieties into the same cube size. Different sweet potatoes cook at slightly different speeds, and even pieces keep everything honest.
- Flip the cubes only once, halfway through. Constant turning prevents the crust from forming that makes these so good.
- Keep a close eye after the thirty-minute mark. Purple sweet potatoes especially can go from caramelized to scorched in a couple of minutes.
Frequently Asked Questions
Where do I find Okinawa sweet potatoes?
Asian markets and well-stocked grocery stores carry them. If you cannot find purple, use three different batches of regular sweet potato and enjoy the same crispy result.
Can I make rainbow cubes ahead of time?
They are best straight from the oven, but you can roast them earlier in the day and rewarm on a hot sheet pan for five minutes to bring the crispness back.
What oil works best for roasting?
Any oil with a high smoke point, since the oven runs at 425°F. Olive oil, avocado oil, or melted coconut oil all give clean, crisp edges.
Recipe Card

Ingredients
Method
- Preheat oven to 425 degrees.
- Place cubes in large mixing bowl and drizzle with oil.
- Toss to ensure even coverage. Salt and pepper generously.
- Spread cubes in one layer on baking sheet so they do not touch.
- Bake for approximately 30-35 minutes, flipping cubes half way through. Watch carefully to avoid burning.
- Once cubes are crispy on the outside and tender on the inside, remove from the oven and cool.




