Mince dill (stems and leaves). Make diagonal cuts into baguette 11/2" apart, leaving 1/4" layer on bottom. Repeat at opposite angle, making a crosshatch pattern. Mince garlic. Hold romaine head at root end and halve lengthwise. Core tomatoes and cut into 1/2" dice. Pat steaks dry, and season both sides with 1/4 tsp. salt and 1/4 tsp. pepper.

In a small mixing bowl, combine mayonnaise, buttermilk, 2 Tbsp. olive oil, dill, 1/2 tsp. salt, and 1/4 tsp. pepper. Refrigerate until plating. Heat grill pan or outdoor grill to medium heat.

Place baguette on prepared baking sheet and insert minced garlic into crevices, as evenly as possible throughout bread. Drizzle 1 Tbsp. olive oil into crevices, then add mozzarella as evenly as possible. Gather foil into a loose pouch around bread. Bake until cheese is melted, 7-8 minutes. Open pouch and bake until cheese is lightly browned, 2-3 minutes. Remove from oven and set aside. While bread bakes, grill steaks.

Coat steaks with 1 tsp olive oil and coat grill or grill pan with cooking spray. Place steaks on hot grill and cook undisturbed until browned, 4-5 minutes. Flip, and cook until steaks reach a minimum internal temperature of 145 degrees, 3-5 minutes. Remove steaks from grill and rest 3 minutes. Reserve grill or grill pan; no need to wipe clean.

Brush 1 tsp. olive oil on cut side of romaine halves. Prepare grill again with cooking spray. Place romaine halves on grill, cut side down, and grill undisturbed until slightly charred, 1-2 minutes. Remove from grill, let cool slightly, then coarsely chop.

Place charred romaine on a plate. Add tomatoes to salad and drizzle with dressing. Slice steaks into 1/2" slices if desired and place on salad. Halve cheesy garlic bread on an angle and serve on the side.