For the raw vegetable boats, clean carrots and celery and cut into fine sticks. Mix with lemon juice and salt, steep for 30 minutes and drain. Rinse mung bean sprouts in a colander in cold water and drain.
Remove leaves and root end from radishes, wash, dry and slice. Peel the young onion, cut into fine rings and fold into the carrot-celery mixture with the bean sprouts, parsley and radish.
For the sauce, mix lemon juice, honey, a little water, salt, pepper and olive oil. Chop garlic and chili and stir in.
Divide the vegetable mixture among the lettuce leaves and drizzle each with 1 tsp of sauce. Place the boats on serving plates and serve with the remaining sauce.