I did create the ultimate steak sandwich, mind you, and it was a winner at Stephanie's Restaurant for many years. Although there were many copies around town, few understood that the secret was to seal the meat, then slice it open so that the gorgeous juice seeped through the buttered spinach and moistened the well-toasted sourdough bread.
1 slice sourdough bread
4-6 flat mushrooms
20g softened butter
½ cup water
freshly ground black pepper
1 x 160g slice fillet steak
1/4 cup caramelised onion
1/2 cup well-squeezed cooked spinach
Preheat a chargrill pan and toast bread on one side. Paint untoasted side with oil and set aside.
Cook mushrooms in a small frying pan with butter and water until juices run and mushrooms look shiny. Keep warm.
Season steak and grill quickly, turning once (about three minutes each side for medium, two minutes each side for medium-rare). Keep warm.
Reheat mushrooms, shaking pan until all the water has evaporated. Remove from heat.
Quickly grill or toast oiled side of bread. Warm the onion. Reheat spinach and pile on toast.
Slice meat through the centre and place cut-side down on top of spinach. Place mushrooms alongside meat. Pile on the onions and season with sea salt and freshly ground black pepper.