In a small bowl combine sugar and chili powder. Sprinkle sugar mixture evenly over pineapple slices. In a 12-inch nonstick skillet cook pineapple slices over medium-high heat for 8 to 10 minutes or until golden brown, turning once. Remove from heat. Cool 10 minutes. Cut pineapple slices into 1-inch pieces.
In a large bowl whisk together olive oil, white wine vinegar, orange juice, cilantro, garlic, salt, and pepper.
Add pineapple, onion, sweet pepper, avocados, and blackberries. Toss gently to combine. Add lettuce. Toss gently until mixture is just coated.