Prepare the salsa by combining red onion, pineapple, jalapeno, fresh cilantro, lime juice and salt, in a small bowl, mix well. Let rest and set aside to use as topping.
Mix together garlic, soy sauce, brown sugar and water.
Add oil to a large skillet and cook pork strips over medium high heat until brown, about 3 minutes per side.
Add soy sauce and brown sugar mixture to the pan. Season with salt, pepper and red pepper flakes.
Mix until evenly coated and let cook for about one minute. Stir again and let cook for another minute, don’t overcook.
Heat another skillet and toast the tortillas until slightly warm, about 20-30 seconds per side.
Assemble each tortilla with pork and top with pineapple salsa. Drizzle with sriracha mayonnaise and finish off with shredded manchego cheese.