Place zucchini* in a colander set over a bowl and sprinkle with 2 tsp. salt. Toss and let stand about 15 minutes to draw out excess liquid.
Prep ingredients while zucchini is draining: dice onions, mince garlic, and chop tomatoes.** Slice corn off of cobs if needed.
Heat oil in a large nonstick skillet over medium-high heat. Add the onion and garlic. Sauté about 3 minutes until soft.
Add zucchini and corn; sauté another 3 minutes until just crisp-tender. Remove from heat.
Add diced tomato, 1/2 of the crumbled feta and stir into vegetables to heat through.
Season to taste (be careful, the feta will add saltiness) .
Spoon into a serving bowl and top with remaining cheese.
*Tip: discard the seedy, mushy middles before dicing, especially with larger zucchini.**Remove seeds when chopping tomatoes to decrease moisture.***Because of the varying saltiness of feta cheese, this really is a "salt to taste" recipe.