Lemongrass Skirt Steak Skewers

Name: Lemongrass Skirt Steak Skewers
Ingredients: 2 pounds skirt steak, preferably Angus, about 1/4 inch thick, silver skin removed; 1 cup finely chopped cilantro stems; 1/2 cup Asian-style lager beer (such as Lucky Buddha); 4 garlic cloves, finely chopped; 2 tablespoons oyster sauce (such as Lee Kum Kee Panda Brand Oyster-Flavored Sauce); 1 1/2 tablespoons granulated sugar; 1 1/2 tablespoons fish sauce (such as Viet Huong Three Crabs Brand); 1 tablespoon finely chopped lemongrass; 1 1/2 teaspoons black pepper; 20 (6-inch) flat bamboo skewers, soaked in water for 1 hour; Grapeseed oil, for grill grates; 1 3/4 teaspoons kosher salt; Mixed microgreens or thinly sliced scallions, for garnish