Cowboy Steak with Roasted Shallots and Watercress Salad

Name: Cowboy Steak with Roasted Shallots and Watercress Salad
Ingredients: One 2 1/2-inch-thick, 30-day dry-aged Tomahawk steak (see Cook’s Note); Kosher salt; Unsalted butter, to taste; 3 to 4 cloves garlic; 1 sprig fresh rosemary; Smoked flaky salt, preferably Smoked Maldon; 2 tablespoons extra-virgin olive oil; 1 lemon, juiced; 8 shallots, cut in half through the root, skins left on; 2 tablespoons olive oil, plus more for finishing; 5 cloves garlic, peeled; 1 teaspoon fresh thyme leaves; Kosher salt and freshly cracked black pepper; 1 tablespoon balsamic vinegar; 1 teaspoon chopped fresh rosemary; 1/2 cup extra-virgin olive oil; 1/4 cup champagne vinegar; 1 tablespoon honey; 2 teaspoons Dijon mustard; 2 teaspoons low-sodium soy sauce; 2 teaspoons balsamic vinegar; 1 teaspoon miso paste; 1/2 teaspoon kosher salt, plus more to taste; Freshly ground black pepper; 1 clove fresh garlic, finely grated; 1 bunch watercress (not baby watercress)