How to Make It
Soak cipollini in a bowl of boiling water for 1 minute. Drain. Trim top and root ends from onions; peel. Cut each onion in half crosswise.
Heat a large nonstick skillet over medium-high heat. Add 2 teaspoons olive oil; swirl to coat. Place half of onions, cut sides down, in the pan, and cook 2 minutes on each side or until browned. Remove from pan. Repeat procedure with remaining 2 teaspoons oil and remaining onions. Return onions to pan, and sprinkle with vinegar and brown sugar. Swirl to melt sugar and coat onions with syrupy mixture. Stir in salt and pepper. Serve cipollini hot or at room temperature.