Preheat oven to 400ºF.
Line a large rimmed baking sheet with parchment paper.
In a small bowl, combine the chili powder, paprika, garlic powder, cumin, salt and pepper. Remove and set aside ½ teaspoon of the seasoning mix.
Place thinly sliced peppers and onions onto one end of the baking sheet. Drizzle with 1 tablespoon oil plus the seasoning mix and toss well to coat.
On the other end of the pan, add riced cauliflower. Toss with the remaining 1 tablespoon of oil.
Place the baking sheet in the preheated oven and bake for 15 minutes, stirring halfway through (stir them both, but don’t stir them together).
While the vegetables bake, make the homemade chipotle ranch dressing, if using by adding the juice of ½ lime and a pinch of chipotle powder to our Homemade Paleo Ranch Dressing. Or substitute your favorite store-bought ranch dressing.
After 15 minutes, remove the baking sheet from oven. Arrange the shrimp in the center of the pan in a somewhat single layer to promote more even cooking of the shrimp. Sprinkle the shrimp with reserved ½ teaspoon of seasoning mix.
Return the pan to the oven and bake an additional 10 minutes, stirring the shrimp if needed to ensure they’re all cooked through (i.e. pink and no longer opaque).
Remove the pan from the oven. Season the riced cauliflower with salt and pepper to taste.
To serve, divide the cauliflower rice among 4 serving bowls. Top with the pepper and onion mixture and shrimp.
Drizzle with Chipotle Ranch Dressing, if desired. Sprinkle with fresh cilantro and serve with guacamole, fresh lime wedges, and/or salsa or pico de gallo for serving.
Store any leftovers in an airtight container in the refrigerator for up to 4 days.
