Heat oil over medium heat in a large pan.
Add onion and sauté for about 5 minutes or until they're translucent and start to brown around the edges.
Add minced garlic and cook for about 30 seconds to 1 minute, the garlic will become fragrant.
Add the chopped calabacitas or zucchini, corn, and chopped chile to the pan. Season with salt to taste and cook for about 10 minutes stirring occasionally.
Add tomato to the mixture and cook for about 1 to 2 minutes.
Serve and top with crumbled queso fresco, queso cotija añejo, or parmesan cheese.