Heat a large skillet over moderately high heat. Add sausage and stir-fry, breaking it up, until it is cooked through and beginning to brown, 8 to 10 minutes. Stir in the water chestnuts and remove from the heat. Transfer to a serving bowl.

While the sausage cooks, separate the lettuce into leaves and arrange on a platter. Place the cucumbers, mangoes, scallions, limes and chili sauce into separate bowls.

To serve, allow everyone to make their own lettuce wraps by filling a leaf of lettuce with sausage, cucumber, mango, scallion, a drizzle of chili sauce and a squeeze of lime.