Bring the chicken broth and coconut milk to a boil in a medium saucepan. Add the rice, then cover, reduce the heat and cook for 20 to 30 minutes. Add salt and pepper to taste. Set aside.
Slice the pineapples 1/2- to 3/4-inch thick and grill for 5 to 7 minutes per side. Let cool, then cut away and discard the rind and core. Cut into large pieces and set aside.
Combine the vinegar, sugar and 1/4 cup salt in a bowl. Thinly slice the serranos and add to the pickling liquid. Let sit at room temperature for 20 to 40 minutes. Drain.
Add the garlic and butter to a large skillet over medium heat; cook until the butter is melted and the garlic has browned. Stir in the juice of 3 of the lemons and the cilantro and parsley. Add the prawns and cook just halfway through. Remove the prawns from the garlic butter, thread onto skewers and grill until fully cooked. Meanwhile, continue to cook the garlic butter sauce for another few minutes and then strain.
Toss the arugula with the juice of the remaining 2 lemons and some salt.
To serve: Plate a small portion of arugula, add 1/4 cup or less of coconut rice, and top with 3 prawns. Spoon over 2 tablespoons of the garlic butter sauce, then add a few pieces of grilled pineapple and pickled serrano.
This recipe was created by a contestant during a cooking competition. It has not been tested for home use.