Warm the olive oil in a medium skillet over medium-high heat. Add the onions and cook until starting to soften, 2 to 3 minutes. Add the yellow squash and zucchini, sprinkle with salt and pepper and stir and cook for 3 to 4 minutes. Remove from the heat and set aside.
Grill the tomato slices on a grill pan or simply sear them in a hot skillet. Remove and set aside.
Bring a medium saucepan of water to a gentle boil. Add the vinegar. Use a wooden spoon to carefully stir the water into a circular "whirlpool." Crack the eggs into the water and allow them to swirl around in the water until they begin to set. Let them stay in the water for 1 minute, then remove them with a slotted spoon and set on a plate. If the eggs need to be cooked longer, just add them back to the water for 30 seconds at a time.
Spoon the vegetables on a plate or in a bowl and set the eggs on top. Lay the tomato slices on the side. Place the cheese slice on the side. Sprinkle the eggs with salt and pepper and serve!
Recipe courtesy of Ree Drummond