Arrange bacon on slotted broiler pan or on rack arranged over baking sheet and bake under the potatoes for 12-15 minutes until crisp. Remove and cool then chop.
Preheat grill pan over medium-high heat or prepare outdoor grill.
Take the chill off the steaks and allow them to come to room temperature. Pat the meat very dry then season with salt and pepper. Finely chop the rosemary. Grate or finely chop 1 large clove of garlic and mash the rosemary with the paste. Place in small bowl and cover with EVOO. Dress the meat with a brush of rosemary oil and grill 8-9 minutes total for medium-rare, basting occasionally with the rosemary oil. Grill 12-15 minutes turning occasionally for medium-well doneness. Let steaks rest to allow juices to redistribute, then cut the meat away from the bone and thinly slice against the grain.
Grate shallot into bottom of a salad bowl using a Microplane or small side of a box grater. Place tomato paste in a small cup and add a splash of very hot water, stir to combine and add to bowl along with mustard, Worcestershire and vinegar. Whisk in the EVOO, about 1/3 cup. Season the dressing with salt and lots of pepper. Add romaine, tomatoes, onions, watercress, potatoes and bacon to the bowl and toss to combine.
Arrange the salad on dinner plates. Dress the meat with any remaining rosemary oil. Divide the sliced meat into 4 portions and arrange along the salad with a head of roast garlic to eat with the meat.