Whisk together mayonnaise, lemon juice, lemon peel and cayenne pepper in medium bowl. Mix in crabmeat and chopped green onions. Season crab salad to taste with salt and pepper.
Spread butter on insides of hot dog buns. Warm large skillet over medium heat 1 minute. Place buns, buttered side down, in preheated skillet and toast until golden, about 5 minutes. Place 2 toasted buns on each of 2 plates. Place 1 lettuce leaf inside each bun. Divide crab salad among buns and serve.