A tasty white fish recipe that's as easy as... well, fish.
Preheat an oven to 350°F (175°C).
Heat 1 tablespoon olive oil in a large skillet over medium-high heat. Cook onion and red pepper in the oil until onion is tender and golden, and peppers are slightly soft, about 10 minutes.
Stir balsamic vinegar into the vegetables; season with salt and pepper.
Rub tilapia filets with 2 teaspoons olive oil and a sprinkle of salt and pepper. Place fillets in a small baking dish, and top with the balsamic onion mixture. Sprinkle fish evenly with feta cheese.
Bake in preheated oven until fish flakes easily. Serve on top of salad greens.