1. Preheat the oven to 180°C.
2. Wash and peel the sweet potato, then cut it into small, baby-friendly chunks.
3. Wash the eggplant and cut it into small, baby-friendly chunks.
4. Wash the cauliflower and break it into small florets.
5. Place the sweet potato chunks, eggplant chunks, and cauliflower florets on a baking sheet. If using olive oil, drizzle a small amount over the vegetables to help with roasting.
6. Roast the vegetables in the preheated oven for 25-30 minutes, until they are soft and easily mashable with a fork.
7. While the vegetables are roasting, take the turkey breast fillet and cut it into small, baby-friendly strips or chunks.
8. In a small frying pan, lightly sauté the turkey pieces on medium heat until fully cooked through. This should take about 8-10 minutes.
9. Once the vegetables are roasted and the turkey is cooked, allow everything to cool slightly until they are safe for baby to touch and eat.
10. Serve the turkey and roasted vegetable medley on your baby's high-chair tray, allowing them to explore and self-feed. Make sure the pieces are soft enough for gumming and chewing.

Summary:
This Turkey and Vegetable Medley is a balanced and nutritious meal, rich in vitamins and minerals, essential for your baby’s growth and development. The mixture of sweet potato, eggplant, and cauliflower provides a variety of textures and flavors, while turkey adds a good source of lean protein.

Storing Options:
Any leftovers can be stored in an airtight container in the refrigerator for up to 2 days. Make sure to reheat the food to an appropriate temperature before serving it again to your baby.

Possible Side Effects/Allergies:
Always check for any signs of allergic reactions when introducing new foods to your baby. Common signs include rash, swelling, or digestive issues. If your baby shows any adverse reactions, consult a pediatrician immediately. Be cautious about the size of the food pieces to prevent choking hazards.