Blend salt, sugar, and dry spices. Sprinkle salmon side with vodka, then coat fully with seasoned salt mixture. Top with fresh herbs (if desired) and sliced lemon. Cover with plastic wrap and refrigerate. Allow salmon 3 days to cure. Once curing is completed, wash salt mixture from fish and cut into thin slices. Finished gravlax might be served as part of a salad, on thinly sliced toast, or on bagels with cream cheese.