Wash and dry all produce. Preheat the oven to 400 degrees. Halve, peel, and thinly slice the onion. Heat a large drizzle of olive oil in a large pan over medium heat. Add the onion and 2 teaspoons sugar. Cook, tossing, for 6-8 minutes, until caramelized. Season with salt and pepper. Remove from the pan and set aside. TIP: For a bolder flavor, add 1 Tablespoon balsamic vinegar to the pan after the onions are caramelized, then reduce until syrupy.

Mince or grate 1/2 teaspoon garlic. In a large bowl, whisk together 1 Tablespoon tomato paste, 2 Tablespoons balsamic vinegar, 2 Tablespoons olive oil, and as much of the garlic as you like. Season with salt and pepper.

Form the ground beef into two patties, and season on both sides with salt and pepper. In the same pan, heat a large drizzle of olive oil over medium-high heat. Add the patties. Cook 2-4 minutes per side, until almost cooked to desired doneness. Top with mozzarella cheese. Cover the pan for another minute, until the cheese melts.

Toast the ciabatta: While the burgers cook, halve the ciabatta rolls. Place in the oven to toast 3-5 minutes.

Toss the salad: Toss the spring mix into the vinaigrette, and season with salt and pepper.

Place each burger inside a bun, then top with the caramelized onion and a bit of sweet-and-tangy salad. Serve the remaining salad on the side and enjoy!