Finely chop the shallots.

Heat 2 tablespoons of vegetable oil and 1 tablespoon of butter in a large cast iron skillet over medium-high heat.

Season the skirt steaks with salt and freshly ground black pepper.

Cook the steaks, 2 at a time, until medium-rare, about 3-4 minutes per side.

Transfer the cooked steaks to a plate and cover with aluminum foil to keep warm.

Add the chopped shallots to the skillet and cook, stirring frequently, until softened and browned, approximately 5 minutes.

Pour in the red wine vinegar and cook until the skillet is almost dry, about 4 minutes.

Remove the pan from the heat.

Stir in 3 tablespoons of butter and pour in any meat juices that have accumulated while the steaks were resting.

Season the sauce with salt and pepper to taste.

Spoon the shallot sauce over the steaks.

Serve the steaks over croutons or with French bread.