Drain the tuna. Make sure all the liquid is pressed out of the tuna. Set to the side.
Mix the ingredients. Combine the egg, red onion, lemon juice, dill, and Old Bay seasoning. Stir to combine. Add the tuna and breadcrumbs, then mix well.
Form the patties. Shape the patties to 1 inch thickness and place them on a plate.
Heat the pan over medium heat. Add the coconut oil to the pan and allow it to get hot over medium heat. Gently add the patties to the pan and sear on each side for 3-5 minutes, until golden brown. Using a spatula to flip the patties.
Make the sauce. Combine the sour cream, mayonnaise, dill, lemon juice/zest, garlic, and salt in a blender. Blend the sauce until it is smooth.
Serve. Drizzle the dill sauce over the tuna patties and top with more dill and wedges of lemon. Mangia!