1. In a deep sauce pan or stock pot fill with about 2” of coconut oil and heat to about 350 deg F ( use a candy thermometer to make sure temperature stays even).
2. In a large bowl add 1 cup of the flour and 1 teaspoon salt and ½ teaspoon black pepper. Drain the onions a handful at a time and coat with the flour mixture, gently shake off excess flour and place in a bowl or on a plate. Repeat until the flour mixture gets too wet and then dump out that flour mixture and start over with another cup of flour with salt and pepper added. Repeat until all the onions are coated with flour.
3. Set out a tray lined with paper towels. When the oil is hot, fry about 6-8 onion strings at a time for about 2-3 min. They are thin so they will burn quickly if over cooked. Using a slotted spoon transfer to the paper towels to drain. Repeat with remaining onions. Season with more salt and pepper if desired.
Cook the tuna patties
1. Heat a cast iron skillet over medium and add 1 tablespoon coconut oil. Fry 4 patties at a time, 2 min each side, being careful when turning them so they don’t break apart. Repeat until all are cooked.
Assemble the sliders
1. Spread wasabi mayo on the top and bottom of the slider buns. Place a few avocado slices on the bottom bun, then a tuna patty, a few of the pickled cucumber slices, a pile of the onion strings and top with the other bun. Repeat with remaining sliders. Serve.