2 tablespoons freshly squeezed lime juice (1 medium lime)
2 tablespoons freshly squeezed grapefruit juice (1/2 small grapefruit)
1 teaspoon soy sauce
1 tablespoon fish sauce
1 teaspoon hot chile sauce, such as sriracha
1/8 teaspoon salt, plus extra for salting the grapefruit
1 teaspoon sugar
1 small carrot, grated (1/4 cup)
1/4 cup chopped cilantro stems and leaves
1 avocado, peeled, pitted, and cut into medium dice
1 tablespoon peanut or other high-heat vegetable oil
1/3 cup thinly sliced shallots
1 grapefruit (Texas Ruby Red, if available)
4 large butter lettuce leaves
1/4 cup roughly chopped dry-roasted, salted peanuts, for garnish
1/4 cup loosely packed fresh mint leaves, stacked and cut into thin ribbons, for garnish
1. In a large bowl, mix the lime juice, grapefruit juice, soy sauce, fish sauce, chile sauce, salt and sugar. Add the shrimp, carrots, cilantro and avocado. Mix well and let the shrimp marinate for 20 minutes in the refrigerator.
2. In a medium sauté pan over medium-high heat, add the peanut oil. Add the shallots and cook until they are caramelized, about 10 minutes. Let them cool and then add them to the shrimp mixture.
3. Cut the peel off the grapefruit, making sure to remove any of the white bitter pith from the flesh. Slice the grapefruit horizontally into 1/2-inch rounds and remove any seeds. Then slice them into 1/2-inch-wide strips, and finally, cut them crosswise into medium cubes. Salt the cubes lightly and set aside.
4. Place the lettuce leaves on a large platter. Spoon the grapefruit and then the shrimp mixture evenly over the leaves, drizzling excess marinade all around the platter. Garnish with the peanuts.