Preheat the oven to 450°F. Spray a muffin tin with 2- to 3-inch-wide bottoms and set aside with a second muffin tin that's the same size, if you have one. 

In a large bowl, mix the pork, ginger, green onions, soy sauce and sriracha (if using) by hand. Using a cookie scoop or your hands, make about twelve 2- to 3-ounce balls. Place the balls in the prepared muffin tin and, using the second muffin tin (if you have one), smash the balls to flatten. If you only have 1 muffin tin, use the bottom of a bottle, such as a sriracha bottle; just cover it with a piece of plastic wrap first.    

Bake the smashed patties until cooked through and browning on the edges, 5 to 7 minutes.    

Meanwhile, spread the rolls with mayo and toast on a sheet pan in the oven.    

When the burgers are ready, place each one on a toasted roll and top with lettuce, avocado, kimchi, cilantro and pickled ginger. Alternatively, you can make a "burger bar" and have all the toppings nicely laid out for everyone to make their own burger. Don't forget the extra sriracha!