Steak should be 2 cm thick. * Onion should be thickly sliced. ~------------------------------------------------------------------------Cut steak into 4 pieces; rub with salt and pepper. Heat butter in large frying-pan until hot but not brown. Brown meat on both sides; remove to platter. Add sliced onions to frying-pan and fry lightly; remove from pan. Add water to frying-pan, scraping pan to loosen any bits of beef. Return meat to pan; cover with onion slices. Add vinegar, mustard, bay leaf and cloves. Cover and cook slowly 1.5 hours or until tender, turning every half hour. Place steaks on serving platter. Remove bay leaf and cloves and place onions on platter. Granish each steak with 1 spiced onion and 3 pimiento strips.