Lay the lettuce leaves across a large platter. Arrange the cucumber, mango slices and shallots over the lettuce.
In a blender, combine the lime juice, shallots, fish sauce, sugar, garlic, cilantro, chiles, and peanut oil. Blend on high speed until well combined and the sugar is dissolved.
In a bowl, toss the shrimp with the Essence, salt, palm sugar, and cayenne to coat. Heat a wok or large, heavy, skillet over high heat. Add the oil and when very hot, add the shrimp and sear until cooked through, about 2 minutes per side. Remove from the pan.
Arrange the shrimp decoratively over the greens and mango and drizzle with the dressing. Garnish with the mint and green onions and serve.
Yield: 4 servings