Add all ingredients except basil into a large slow-cooker, cover and cook. Cook for 3-4 hours on high or 5-6 hours on low). The ratatouille is ready when the vegetables have softened, but aren't mushy. If you're worried about the ratatouille being too watery, remove the slow cooker lid and cook on high for the last hour. Just before serving, gently stir in fresh basil. Serve warm or cold as a side or over a whole grain like quinoa or rice as a main entree.
