Grilled Steak Salad with Beets and Scallions

Name: Grilled Steak Salad with Beets and Scallions
Ingredients: ½ cup beef or chicken stock or low-sodium chicken broth; 1 large egg yolk*; 1 teaspoon Dijon mustard; ½ cup vegetable oil; 2 teaspoons fresh lemon juice; 1 small garlic clove, finely grated; Kosher salt and freshly ground black pepper; 1 pound tri-tip, New York strip, or skirt steak; 1 garlic clove, halved; 4 tablespoons olive oil, divided; 1 bunch scallions or ramps; 1 bunch spicy greens (such as arugula or mizuna); 1 tablespoon fresh lemon juice; 3 beets, peeled, thinly sliced; 1 tablespoon balsamic vinegar