1. Place the steak in the freezer to chill for 1 to 2 hours to make it easier to slice.
   Meanwhile, make the marinade. In a blender or food processor, combine the pineapple, coconut aminos, dates, white parts of the green onions, the garlic, ginger, sesame oil, salt, black pepper, and pepper flakes and process until smooth.
2. Using a very sharp knife, slice the steak against the grain into 1/8-inch-thick strips. Transfer the strips to a large bowl and pour the marinade over the top. Use your hands to rub the marinade into the meat. Cover and marinate at room temperature for 30 minutes.
3. Meanwhile, place the lettuce leaves and cucumber slices on a large cutting board. Put the kimchi and any additional toppings in small serving bowls.
4. Heat a large skillet over high heat until hot. Working in two batches to avoid crowding, remove the meat from the bowl, scraping any excess marinade back into the bowl, add the strips to the pan in a single layer, and fry, undisturbed, for 1 minute, until browned on the underside. Using tongs, flip the steak and cook, undisturbed, for 1 minute more, until browned on the second side. Using the tongs, transfer the steak to a plate and repeat with the remaining strips. Then return all of the browned meat to the pan and cook, stirring, for 1 to 2 minutes, until most of the liquid has evaporated.
5. Sprinkle the steak with the sesame seeds and green parts of the green onions. Serve immediately from the skillet (to keep the meat hot) with lettuce, cucumbers, kimchi, and other toppings.

Sriacha Aioli:

1. To make the aioli, in a small bowl, stir together the mayonnaise, Sriracha, lime juice, salt, garlic powder, cayenne, and pepper flakes. Cover and refrigerate until ready to serve or for up to 1 month.