Combine the mustard and Worcestershire sauce and coat the steaks. Season with salt and pepper and reserve 2 tablespoons of this mixturefor the sauce.
Cut the onions and peppers into small cubes. Brown them,then add the broth, herbs, the rest of the mustard-Worcestershire mixture, theTabasco and reduce by half over low heat.
Add the cream and keep warm.
Grill the flat iron beef steaks to your liking (barbecue,grill pan, grill, etc.).
Serve the steaks covered with sauce, accompanied by a nicesalad and potatoes (fries and other sautéed potatoes).