Whisk together the pineapple juice, soy sauce, sesame oil, apple cider vinegar, and ginger in a small bowl. Trim the skirt steak of any silver skin and put in a large ziptop bag, add the marinade and seal tightly. Marinade the steak in the fridge overnight.
Heat a grill to high direct heat. Grill the pineapple for the salsa directly on the grill grates for 2 to 3 minutes per side until charred on some bits and softened. Remove from the heat and cool before dicing. Combine the diced pineapples with the onion, red pepper, jalapeno, Salt Pepper + Three Chiles, salt, pepper, lime juice, and cilantro.
Remove the skirt steak from the marinade and pat dry with paper towels. Cook the skirt steak over hight direct heat, turning often, until charred, about 8 minutes total. Remove from the heat and slice the skirt steak against the grain. Serve the skirt steak over the rice with the salsa, scallions, and sesame seeds for garnish.