In a resealable bag, add in garlic, thyme, Worcestershire, hot sauce and combine.
Add in the steak into the resealable bag and turn to coat evenly.
Allow the steak to marinate for 2-3 hours.
Heat up a heavy skillet over medium-high heat and sear the steak for 3-5 mins. per side for medium-rare (less or more time, depending on taste preference).
Remove from heat and allow the meat to rest before cutting.
Toss the tomatoes in olive oil to coat, then roast at 415°F (210°C) for 10-15 mins.
In a small bowl, whisk together the mayonnaise, sour cream, and lemon zest, then evenly divide, and spread over the 4 slices of bread.
Slice up the steak and evenly layer over the remaining 4 slices of bread then top with the blue cheese crumble and layer with watercress, red onions, and roasted tomatoes.
Complete by topping with the reserved four slices of bread which were spread with the mayo mixture.