How to Make It
Stir eggplant and tomatoes together in a slow cooker.
Warm 1 Tbsp. oil in a large nonstick skillet over medium heat. Add peppers and onions to skillet and cook, stirring occasionally, until slightly softened, about 3 minutes. Stir in garlic and crushed red pepper, season lightly with salt; cook, stirring, until garlic is tender, about 30 seconds longer. Stir vegetables into eggplant mixture in slow cooker.
Wipe out skillet. Warm remaining 1 Tbsp. oil in same skillet. Add sausages; brown, turning once, about 4 minutes total. Nestle sausages on top of vegetables in slow cooker.
Cover and cook on low until vegetables are soft and sausages are cooked through, 4 to 5 hours. Season with salt and pepper and serve.