Balsamic and Soy Marinated Skirt Steaks with Charred Peppers

Name: Balsamic and Soy Marinated Skirt Steaks with Charred Peppers
Ingredients: 1/4 cup balsamic vinegar; 1/4 cup low-sodium soy sauce or tamari; 1 1/2 teaspoon plus a pinch of kosher salt, divided; 2 pounds skirt steak, trimmed and cut into 6-inch pieces; 1 pound mini sweet peppers; 1 (13-ounce) onion, cut into 1/2-inch-thick slices; 1 tablespoon extra-virgin olive oil; 1 teaspoon black pepper, divided; 1/2 cup chopped fresh cilantro; 2 tablespoons chopped fresh chives; 2 tablespoons fresh lemon juice; 1 garlic clove, smashed; Grilled ciabatta, for serving