Slowly cooked, onions undergo a lovely transformation, becoming silky, nutty, and amber brown. This process, caramelization, occurs as the onions' sugars release and cook. Here's how.:
Peel and trim onions, and vertically slice 1/4 inch thick.
Why? Slicing lengthwise, and not too thinly, maintains the onions' cell structure and keeps them from becoming mushy.
Heat a large nonstick skillet over medium-high heat. Add oil to pan; swirl to coat. Add onions and 1/4 teaspoon salt. Cook 8 minutes, stirring.
Why? A nonstick pan enables long, slow cooking using just a little oil. Beginning over medium-high heat jump-starts caramelization; the salt helps to quickly extract the onions' sugary juices.
Reduce heat to medium-low. Cook for 35 minutes or until deep amber, stirring. Use for pizzas, panini, or pasta tosses.
Why? Milder heat prevents scorching as the onions' natural sugars continue to release and brown. Flavors mellow and the onions shrink and soften.