Preheat grill or oven to medium-high heat (375°F). Season chicken with southwest seasoning and cook until fully cooked (6-7 minutes per side on the grill or 20-25 minutes in the oven). Let rest for a few minutes.
Slice the cooked chicken into thin strips. In a skillet over medium heat, sauté bell peppers and red onion in olive oil until tender (about 5 minutes).
In a blender, combine avocado, Greek yogurt, lime juice, cilantro, and salt; blend until smooth.
Lay out each tortilla and layer with sliced chicken, sautéed veggies, and drizzle with avocado dressing. Roll tightly.
Slice diagonally and serve with extra avocado dressing on the side.
