Drain your tuna by placing it in a fine mesh sieve lined with a paper towel. Squeeze out as much water from the tuna as possible. Add drained tuna and all patty mix ingredients to a large bowl. Use your hand to mix until everything is combined.
Divide the mix into 4 balls and shape into ½ inch thick patties. Place patties on a sheet pan or large plate and set aside.
Mix melted butter and 1 Tbsp chili crisp. Brush chili crisp butter onto buns and toast face down on a large skillet over medium heat. Set warm buns aside.
Fill a heavy bottomed pan (dutch oven or cast iron pan) with neutral oil until the oil reaches 1 inch high in the pan. Set pan to medium heat until a thermometer reaches 360°F.
Set up dredging station: Place 1 cup flour, salt, and pepper in a shallow dish. Crack egg and 1 Tbsp milk in another shallow dish. Whisk until incorporated Place panko breadcrumbs in a third shallow dish. Place a clean pan or plate at the end of the station for the final breaded patties to rest on.
Take a tuna patty and dip both sides in the flour and brush of excess. Transfer to egg mixture, ensure the patty is covered all around, and let excess egg drip. Transfer to panko breadcrumbs and press crumbs into patty. Place on the clean pan or plate. Repeat with all the tuna patties.
Place two patties in the hot oil and fry for 3 minutes, or until golden brown, on each side. Repeat with other patties and transfer fried patties to a wire rack.
Assemble burgers: Spread tartar sauce on bottom buns, place patty on top, squeeze fresh lemon juice on top of patty, spoon more tartar sauce on the patty, drizzle chili crisp onto the tartar sauce, and finish the burger with the top bun. Enjoy as soon as possible after frying!