Add oil to a skillet and heat over medium.
Unwrap fish and lay in hot skillet. You may need to slice the fillet in two or three slices to fit, depending on the size of your skillet.
Saute for three minutes then using a spatula, flip and cook for another three minutes or until fish is has a golden exterior and sides of the fish look opaque or solid white.
While fish is cooking, toast your buns.
Remove fish from heat and let rest on a plate for a minute.
Place a chunk of fish fillet on each toasted bun with a slice of lettuce and any condiment you might want to use.
Serve while still warm.
Wrap up any uneaten fish and refrigerate for up to a day.