Cook rice according to package directions, omitting salt and fat. Cool. Combine rice and next 5 ingredients (through sliced almonds).
Combine mint, juice, oil, salt, and pepper in a small bowl, stirring with a whisk. Drizzle mint mixture over rice mixture; toss well. Cover and chill. Place 1 lettuce leaf on each of four plates. Spoon 1 1/2 cups rice mixture onto each lettuce leaf. Garnish with mint sprigs, if desired.