Season the fish on both sides with salt and pepper. Heat oil and 1 tablespoon of the butter together in a saute pan over medium-high heat. Saute the fish 2 minutes on each side, until it has a crispy brown crust
. Remove from the heat.
In a separate saute pan set over medium-low heat, melt the remaining tablespoon of butter. Lightly toast the tortillas on both sides. Keep them warm on a plate by covering with a clean kitchen towel.
Using a fork, flake the fish and place a small amount on each tortilla. Top with guacamole, tomatoes, onions and cilantro; roll up.