Preheat the oven to 400°F.
Combine diced sweet potato and chopped cauliflower in a medium mixing bowl.
Drizzle with 2 tablespoons of olive oil, harissa, salt, and pepper.
Mix well, so harissa is evenly coating all the vegetables.
Roast for 30 minutes.
While cauliflower and sweet potatoes are roasting, rinse the collard green leaves well and set aside to dry.
In a medium sauté pan, heat the remaining tablespoon of olive oil over medium heat.
Add julienned pepper and sauté for about 7 minutes or until softened and starting to brown slightly. At this point, add the minced garlic, baby spinach leaves, a pinch of salt and pepper, and sauté until spinach starts to wilt, about 2 minutes.
Remove from heat.
Remove cauliflower and sweet potatoes from oven and let cool for 1 minute. Split this mixture up between the 4 collard green leaves.
Top each with the peppers, spinach, and salsa and roll the leaves up like a burrito.
Make sure to tuck in the sides so none of this delicious filling drips out!