Learn how to caramelize onions to elevate your favorite meals. The variety, cutting technique, and cooking method all impact taste. To prevent mushy onions, slice them from root to stem between ⅛ to ¼-inch thick. Thinner slices may burn or soften too much. Onions contain about 1% protein, contributing to caramelization and Maillard browning when heated, enhancing flavor complexity. Caramelization starts as onions lose moisture, forming a brown fond at the pan's bottom. Deglazing is key to ...