How to Make It
In a large saucepan, bring 2 inches of water to a boil. Add the mushrooms, cover partially and cook until tender, about 4 minutes. Drain the mushrooms.
In a mortar, pound the garlic and sugar to a paste. Add the chile and pound to blend. Add the lime juice and fish sauce and mix well.
Transfer the mushrooms to a bowl. Add the shallots and dressing and toss gently to coat. Add the mint and toss again. Line a platter with the lettuce leaves and mound the salad on top. Serve at room temperature, with rice.