Preparation Cook beans in boiling salted water until crisp-tender, 4 to 5 minutes. Drain. Rinse with cold water; pat dry. DO AHEAD Can be made 4 hours ahead. Layer between paper towels and refrigerate. Melt butter in large skillet over medium-high heat. Add beans, thyme, and peel; sprinkle with salt and pepper. Toss until heated, about 5 minutes.
Preparation Cook beans in boiling salted water until crisp-tender, 4 to 5 minutes. Drain. Rinse with cold water; pat dry. DO AHEAD Can be made 4 hours ahead. Layer between paper towels and refrigerate. Melt butter in large skillet over medium-high heat. Add beans, thyme, and peel; sprinkle with salt and pepper. Toss until heated, about 5 minutes.