Slice zucchini and yellow squash into ¼-inch thick slices. Then cut each round in quarters.
Cut the yellow onion in half and then cut along the grain into thin slices.
In a large skillet over medium heat, add vegetable oil and minced garlic. Add zucchini, yellow squash, corn, along with onion. Cook, stirring occasionally.
Cook to the desired consistency (we like ours a little more cooked and soft and cooked for about 15 to 18 minutes). NOTE: Liquid will evaporate the longer you cook it.
Remove from heat and top with shredded cheese or grated Parmesan cheese. Season to taste and serve warm.
