1. Preheat broiler. Cook 1 cup quinoa according to package directions, replacing the water with low-sodium vegetable broth; keep warm.
2. Meanwhile, place 4 ears shucked fresh corn on a foil-lined baking sheet. Broil 4 to 5 inches from the heat about 8 minutes, turning occasionally, or until lightly charred. Let cool slightly, then cut kernels from cobs.
3. In a small saucepan, combine one 15-oz. can reduced-sodium black beans (rinsed and drained), the juice and zest of 1 lime, 1 Tbs. olive oil, and 1 tsp. ground cumin. Cook, stirring occasionally, over medium-low heat until heated through.
4. Divide quinoa among 4 bowls. Set out roasted corn, black bean mixture, 1 sliced avocado, 2 oz. crumbled Cotija cheese, 1/2 cup roasted salted pepitas, crushed tortilla chips, and lime wedges and let everyone assemble their own bowls.