Season the steaks with black pepper. Heat a large non-stick frying pan until really hot, and cook the steaks for 2-3 minutes, without moving them. Sprinkle with salt, turn over and cook for 2-3 minutes more; keep warm.
Turn down the heat and fry the chopped shallots in the butter until softened, about 2 minutes. Pour in the red wine, add the thyme and reduce by two-thirds. Stir in the redcurrant jelly, mustard and salt and pepper. Return the steaks to the pan, heat through in the sauce and serve.