Lay 5 tortillas in a skillet in a flour formation. Add your steak, then onions, then peppers, then tomato, coriander and cheese. Pop a final tortilla on top, fold in the rest, then cover with greaseproof and weigh down with something heavy (and oven-proof). Bake for 25 minutes at 200°C.
Meanwhile, make your sauce. Heat your butter over low heat then add your flour. Cook for 30 seconds then add a little milk. Add your milk bit by bit, stirring constantly. Once all incorporated, bring slowly up to a heat until thickened slightly. Turn off the heat, add your hot sauce, stir through, then begin to add your cheese. Keep adding until all incorporated.