1. Preheat the grill to medium-high heat.
2. Place the tomatoes in a large bowl, and sprinkle with 1/2 teaspoon salt. Let stand 10 minutes.
3. Brush corn, onion, and jalapeño evenly with oil. Place vegetables on grill rack coated with cooking spray. Grill corn for 12 minutes or until lightly charred, turning after 6 minutes. Grill onion slices and jalapeño 8 minutes or until lightly charred, turning after 4 minutes. Let vegetables stand 5 minutes. Cut kernels from cobs. Coarsely chop onion. Finely chop jalapeño; discard stem. Add corn, onion, and jalapeño to tomato mixture; toss well. Add remaining 1/2 teaspoon salt, cilantro, and next 4 ingredients (through kidney beans) to corn mixture; toss well. Top with avocado.