Slow-Cooker Chicken Cacciatore With Polenta

Ingredients

• 2 teaspoons extra-virgin olive oil
• 2 cups chopped red bell peppers
• 2 cups chopped yellow onion
• 8 ounces cremini mushrooms, halved
• ½ teaspoon kosher salt, divided
• 3 tablespoons all-purpose flour
• 1 tablespoon tomato paste
• 3 tablespoons minced garlic
• ¼ cup chopped fresh oregano
• ½ teaspoon crushed red pepper
• ½ cup red wine
• 4 pounds bone-in, skinless chicken thighs, trimmed
• 1 (28 ounce) can fire-roasted diced tomatoes
• 1 cup unsalted chicken broth
• ¼ cup drained capers
• ¼ cup pitted Kalamata olives
• 3 cups water
• 1 ⅓ cups uncooked instant polenta
• ¼ cup grated Parmesan cheese
• ¼ cup torn fresh basil