In this recipe, the swordfish steaks are split in half and pounded thin like a traditional schnitzel. It is then dredged in a breadcrumb crust and pan fried, resulting in a crispy and tender fish that is served with a bitter and bright side salad for a satisfying weeknight meal.
Put the red onion in a small bowl and cover with ice water; set aside. Using a sharp knife, slice each swordfish steak in half horizontally to make a total of 4 thin swordfish steaks. Place the fish between 2 sheets of plastic wrap and gently pound to 1/4 to 1/2 inch thick with a meat mallet or heavy skillet.
Divide the flour, eggs and breadcrumbs among 3 shallow bowls. Season the breadcrumbs with 1 teaspoon salt and a few grinds of pepper. Dredge the fish in the flour, shaking off any excess. Dip in the eggs, then coat in the breadcrumbs. Transfer to a plate.
Cook the bacon in a nonstick skillet over medium-high heat, flipping, until crisp, 6 to 8 minutes. Remove to a paper towel–lined plate. Spoon 2 tablespoons of the bacon fat into a small bowl.
Add the olive oil to the skillet and return to medium heat. Add 2 swordfish steaks and cook until crisp, 2 to 3 minutes per side. Remove to a rack set on a baking sheet. Add more olive oil to the skillet if needed and repeat with the remaining 2 swordfish steaks.
Combine the radicchio and butter lettuce in a large bowl. Crumble the bacon into the salad. Drain the red onion, pat dry and add to the salad. Whisk the vinegar and mustard with the reserved bacon fat; toss with the salad. Divide the swordfish and salad among plates.