Combine salt, sugar, dill, and pepper in a small bowl.
Lay a piece of cling wrap 3 times longer than the filet on a long, smooth surface (like a cookie sheet) and sprinkle a 1/2 of the salt/sugar mix on a third of the cling wrap.
Set the filet on the salt/sugar and then sprinkle the rest on top of the filet.
Wrap tightly in the cling wrap, leaving one edge open to drain.
Place on a plate and store in the refrigerator for 5 days with a weight on it, turning daily and draining the liquid off.
After 5 days, the filet should be opaque and a light coral color. With a very sharp knife, cut into slices as thinly as possible.
Put together dressing ingredients in a bowl and whisk until combined, about 30 seconds. Toss the salad with the lemon dressing and lay about a third of the shaved lox on top and garnish with lemon zest.