Preheat the oven to 425 degrees F.

In a small bowl, combine the sour cream, mayonnaise, ranch salad dressing, and finely diced cucumber. Set aside in the refrigerator.

Line a rimmed baking sheet with parchment paper.

Place the salmon filet skin-side down on the baking sheet, brush with 1 Tbsp cooking oil and season with salt and black pepper.

Bake uncovered for 10-15 min, depending on the thickness, just until cooked through.

Discard the salmon skin, flake the meat with two forks. Remove any bones, and allow to cool.

While the salmon cools, heat a medium skillet over medium heat.

Add 1 Tbsp cooking oil, 1 Tbsp butter and the finely diced onion and bell pepper. Cook and stir occasionally until softened about 3-5 minutes, then remove from heat.

In a medium mixing bowl, combine the cooled flaked salmon, cooked onion and bell pepper, Panko bread crumbs, egg yolk, mayo, Worcestershire sauce, garlic salt, and 1/8 tsp black pepper. Stir to combine.

Form into 2 round patties about 1/2" thick. They will be very wet and loose.

In the same frying pan, heat 1 Tbsp cooking oil and 1 Tbsp butter over medium heat.

Carefully move the salmon cakes into the hot oil. Use a spatula or fork to press it back together if needed. Cook about 4-6 min per side or until golden brown and cooked through. If salmon patties brown too quickly, reduce the heat.

Remove the salmon burgers to a paper-towel lined plate to drain.

Place the lettuce leaves on buns, add salmon burgers, Ranch cucumber sauce, and top with the second half of the bun.