Blanche sugar snap peas in salted, boiling water for 45 seconds from the moment peas are added. Do not overcook even briefly or peas will become too soft. Drain and immediately plunge into ice water for several minutes to cool. Do not soak. Drain thoroughly, set aside. Whisk together lemon zest and juice, garlic, salt, pepper and red pepper (if used). Whisk in oil. Toss peas and green onions with dressing; arrange on serving platter, garnish with lettuces (and lemon slices, if desired). Sprinkle with toasted almonds.