Green Beans with Glazed Onions Recipe

Ingredients

• 3 pounds fresh green beans, cleaned and trimmed
• 2 (16 oz) bags frozen pearl onions, thawed
• 1/2 cup balsamic vinegar, divided
• 2 tablespoons butter
• 2 tablespoons vegetable oil
• 1 teaspoon dried thyme
• 1 teaspoon ground black pepper
• 1 teaspoon salt, divided
• 3 tablespoons olive oil
• 1 tablespoon stone-ground mustard
• 1 1/2 teaspoons sugar