Cook the corn. Bring a large pot of salted water to a boil. Add shucked corn and cook 3–4 minutes until bright and crisp-tender.
Drain, cool, and cut the kernels off the cob. If using frozen corn, sauté in a dry skillet over medium-high heat for 4–5 minutes to char slightly.
Prep the veggies. Halve the tomatoes. Dice the cucumber and red bell pepper.
Finely chop the red onion. If using jalapeño, mince it. Add everything to a large salad bowl with the cooled corn.
Make the dressing. In a jar or small bowl, whisk together lime zest (from 1 lime), juice (from 3 limes), olive oil, honey, minced garlic, cumin, 1 teaspoon kosher salt, and several grinds of black pepper.
Taste and adjust acid or sweetness as needed.
Toss and rest. Pour half the dressing over the corn mixture and toss. Let it sit for 10–15 minutes so the flavors mingle. This short rest makes a big difference.
Add herbs and avocado. Gently fold in chopped basil, cilantro (if using), and diced avocados.
Add more dressing to lightly coat. Go easy to keep the avocado intact.
Finish with feta. Sprinkle crumbled feta on top. Add a pinch more salt and pepper if needed.
If you like, reserve a little basil for a fresh, pretty garnish.
Serve or chill. Serve immediately at cool room temperature, or chill up to 2 hours. Bring to room temp before serving for the best flavor.