In a large bowl, whisk together almond meal, lemon zest, 1/4 cup of mayonnaise, egg, dill, and onion. Fold in salmon pieces and mix. Press into burger patties, lay flat on a large plate or baking sheet, and refrigerate for 20-30 minutes.

Heat olive oil in a cast iron pan or griddle on medium high heat, gently place salmon burgers clockwise in pan, cook for 4-5 minutes per side, gently flipping. Remove burgers to a paper towel lined plate.

Whisk together remaining 1/4 cup mayonnaise and the lemon juice. Serve salmon burgers wrapped in butter lettuce leaves with a dollop of lemon-mayo and avocado slices.