Red pepper flakes give this vegan roasted spicy purple cauliflower soup some heat. It is hearty and filling thickened with purple fingerling potatoes.
1–1/2 pounds purple cauliflower, trimmed and broken into florets*
1/2 pound purple fingerling potatoes or purple sweet potatoes, diced
2 tablespoons olive oil
1/4 teaspoon crushed red pepper flakes plus more for serving
1–1/2 teaspoon kosher salt
1/2 teaspoon black pepper
1 small red onion, roughly chopped*
1 garlic clove, crushed
3 cups water
Fresh chives for serving
Preheat the oven to 375 degrees F. Toss the cauliflower and potatoes with 1 tablespoon olive oil, 1/8 teaspoon red pepper flakes, 1/2 teaspoon salt and 1/4 teaspoon black pepper. Roast the cauliflower until it is tender and the florets are starting to brown at the edges, about 25 to 30 minutes.
Heat the remaining olive oil in a large saucepan over medium heat. Add the onions and sauté for 5 minutes until they start to soften. Stir in the garlic and remaining red pepper flakes, salt and pepper and continue cooking for an additional 3 minutes. Add the water cauliflower and potatoes, reserving 1/2 cup cauliflower for garnish. Simmer the soup for 10 minutes.
Carefully transfer the soup in batches to a blender to puree. Return the soup to the saucepan to reheat before serving, Divide into bowls and top with cauliflower, fresh chives and red pepper flakes.
*If you have white, orange or green cauliflower, use a white onion instead of red.