In a medium bowl combine lime juice, oil, and garlic. Brush corn lightly with juice mixture. Sprinkle corn with chili powder. Preheat gas grill. Reduce heat to medium. Place corn on the grill rack directly over heat. Cover and grill for 25 to 30 minutes or until corn is tender, turning occasionally.
Meanwhile, add avocado, sweet pepper, cilantro, and salt to remaining lime juice mixture; toss well. Cut corn kernels from cobs and add to avocado mixture; toss well. Serve with grilled meat, poultry, or seafood.