Slow Cooker Mongolian Beef

Name: Slow Cooker Mongolian Beef
Ingredients: 1 pound steak (sirloin or flank), sliced thinly; 3 tablespoons soy sauce (gluten-free or tamari for gluten-free); 1 tablespoon hoisin sauce (gluten-free for gluten-free); 1 tablespoon brown sugar; 1 teaspoon chill sauce such as sambal oelek; 1 clove garlic, grated; 1 teaspoon ginger, grated; 1 tablespoon cornstarch; 1/3 cup water or beef broth; 1 onion, thinly sliced (optional); 1 carrot, julienned (optional); 1 jalapeno, thinly sliced (optional); 1 teaspoon sesame oil; 1/4 cup green onion, sliced