Preheat the grill: Heat a gas or charcoal grill to medium-high. Clean and oil grates so the corn doesn’t stick.
Season the corn: Brush ears with olive oil and sprinkle with salt and pepper.
Grill to char: Place corn on the grill. Cook 8–12 minutes, turning every 2–3 minutes, until lightly charred in spots and tender.
Make the lime cilantro butter: In a small bowl, whisk melted butter, lime zest and juice, garlic, honey, cumin, chili powder, and a pinch of salt.
Stir in half the cilantro.
Cut the kernels: Let corn cool slightly. Stand each ear in a large bowl and slice kernels off with a sharp knife.
Add the mix-ins: Toss kernels with red onion, bell pepper, jalapeño, green onions, and the remaining cilantro.
Dress the salad: Pour the lime cilantro butter over the warm corn mixture and toss gently. Taste and add more salt, pepper, or lime if needed.
Finish and serve: Fold in avocado and cotija just before serving so they stay intact.
Serve warm or at room temperature.