Steak Kebabs with Fish Sauce Butter

Name: Steak Kebabs with Fish Sauce Butter
Ingredients: 1 cup unsalted butter, softened, divided; 1 1/2 tablespoons finely chopped garlic (about 4 large cloves); 1 tablespoon finely chopped shallot (about 1 small shallot); 1 1/2 teaspoons fish sauce (preferably Red Boat); 1/2 teaspoon Maggi seasoning; 1/4 teaspoon rice wine vinegar; 2 tablespoons finely chopped fresh basil; 1 tablespoon finely chopped fresh cilantro; 1 teaspoon grated lemon zest; 2 1/2 pounds beef sirloin steak (1 to 1 1/2 inches thick), cut into 1 1/2-inch cubes; 1 tablespoon kosher salt, plus more to taste; 1 tablespoon neutral cooking oil (such as canola oil), plus more for grilling