Unicorn noodle spring rolls are a delicious rainbow

These unicorn noodle spring rolls are stuffed with so many colorful vegetables that they look like a bite right out of a rainbow. Accompanied by a Thai-inspired sweet chili sauce, they have just enough kick to keep each bite exciting.

The best part of these spring rolls are the rice noodles that we’re going to change from purple to pink in the blink of an eye. That sounds a lot like magic, but it’s actually the wondrous work of food chemistry. There’s no need to call up your high school science teacher to track down lab ingredients, though: The process is completely natural and needs only ingredients from the grocery store — specifically, rice noodles, purple cabbage and lime. That’s it!

So here’s how this process works. Purple cabbage gets its color from anthocyanin, a pigment that’s an acid/base indicator — meaning it changes color when it comes into contact with something acidic or alkaline. If you add acid, the color will change from purple to pink. If you add a base, such as baking soda, the color will change from purple to blue.

Here’s what you’ll need to make these unicorn noodle spring rolls:

• 1 pack spring roll wrappers
• 1 pack clear or white rice noodles (I used mungbean or glass noodles)
• 1/2 head purple cabbage, chopped
• 1 or 2 limes
• 1/2 cup cucumbers, shredded
• 1/2 cup carrots, shredded
• 1/2 cup cabbage, shredded
• 1/2 cup purple cabbage, shredded
• 1 avocado, thinly sliced
• 3 green onions, chopped
• Pickled ginger

Start out with a few cups of chopped purple cabbage. More cabbage and lower quantities of water will produce a more pigmented dye. Boil the cabbage in water for about eight minutes, or until the water takes on a deep purple hue.

Strain the chopped cabbage out of the pigmented water and discard the cabbage, saving the water. Bring the cabbage water back to a boil and cook the rice noodles as directed on the packaging.

After cooking, the noodles will come out a nice purple hue. Don’t rinse the noodles! (You’d wind up rinsing some of the pigment away, too.) Wait to squeeze lime juice — an acid — on the noodles until after they’re inside the spring rolls; that way, each spring roll gets a little bit of pink and purple. Set the noodles aside.

I like to stuff the spring rolls with as many vibrant and crunchy vegetables as possible. For this recipe, I used avocado, green cabbage, purple cabbage, carrots, cucumbers, pickled ginger and green onions.

Slice all the vegetables into thin shreds and lay them on a plate or cutting board in an assembly line. This is an important step, because you’ll need easy access to all the fillings once you’re rolling. Set the ingredients where you can easily reach them, and clear a space for wrapping your spring rolls. The easiest option is a clean cutting board, but a large plate works, too.

MORE: How to make naturally-dyed rainbow pasta

Add warm water to a large, shallow bowl or pie dish. Fully submerge one wrapper at a time in the warm water. Rub it with your hands, leaving it in the water just long enough to get wet but not soggy, about 15 seconds.

It might feel slightly firm at first, but the wrapper will continue to soften when you lay it on your surface to begin rolling. Don’t leave it in the water for too long, or it will become too soggy and rip as you work with it.

Lay the rice paper wrapper out flat and place the filling in the bottom third of the wrapper. Shoot for a roll about 6 inches long and not too thick. Distribute the ingredients evenly across so that you get a little bit of everything in each bite. Lay out the avocados like little vertical rainbows, and then lay the shredded ingredients on top followed by the unicorn noodles. Add a squeeze a lime across half of the noodles to turn them from purple to pink!

Pull the bottom of the rice paper over the filling, tucking it under to pull the ingredients a bit closer together. Gently pull the left side of the wrapper over the middle and then the right, closing the ends of the roll. Roll it up away from you, gently tucking the filling tightly to maintain the roll’s shape.

Serve these unicorn noodle spring rolls with homemade Thai sweet chili sauce, which you can make ahead of time. You’ll need:

• 1/2 cup rice vinegar
• 3/4 cup water
• 1/2 cup + 2 tablespoons white sugar
• 5 garlic cloves, chopped finely
• 1 tablespoon soy sauce (tamari, if you’d like to keep the recipe gluten-free)
• 2-1/2  tablespoons sambal oelek
• 2 teaspoons arrowroot flour
• 1/4 cup water, as needed

Add the vinegar, water, sugar, garlic cloves and soy sauce to a nonstick pan. Heat over medium heat while stirring to dissolve the sugar.

MORE: This unique, fun and easy unicorn hot chocolate is perfect for kids

Increase the heat to medium-high and bring it to a boil. Let it simmer for about 2 minutes. Add the sambal oelek and mix thoroughly. Let it cook for a few minutes until it’s slightly thickened (2–5 minutes). Mix the arrowroot flour and water into a smooth slurry and add to the sauce. Simmer the sauce for a further 2–5 minutes or until it reaches desired thickness, stirring frequently to prevent burning.

Remember: The sauce thickens as it cools. If it thickens too much, add a little water to thin it out. Pour the sauce into an airtight jar and allow to cool before storing in the fridge for up to a week.

Make these spring rolls shortly before serving. Rice paper becomes fragile as it begins to dry, so they don’t keep well in the fridge. They will also stick together as they dry, so get the spring rolls a bit wet before laying them on a serving platter together. Better yet, keep them separate by serving over a bed of lettuce or cabbage. If you plan to transport these to a party or event, double-wrap them in spring roll paper so they’re a bit sturdier.