Toss shrimp with olive oil, lime juice, garlic, cumin, chili powder, salt, and pepper in a medium bowl. Let marinate for 10–15 minutes.
Heat a grill or grill pan over medium-high heat. Grill the shrimp 2–3 minutes per side, until they are pink and lightly charred. Remove and set aside.
Whisk together olive oil, lime juice, zest, honey, Dijon mustard, garlic, salt, and pepper in a small bowl. Taste and adjust seasoning.
In a large salad bowl, combine mixed greens (if using), tomatoes, corn, red onion, avocado, and cilantro. Drizzle with dressing and toss gently to coat.
Arrange grilled shrimp on top. Serve immediately with extra lime wedges, if desired.