1. Wash the orange thoroughly to remove any pesticides or dirt.
2. Peel the orange and separate it into segments. Remove any seeds and tough membrane.
3. Peel the banana and cut it into smaller pieces.
4. In a blender or food processor, combine the banana pieces and orange segments.
5. Blend until you achieve a smooth puree consistency suitable for your baby's age and texture tolerance. If needed, you can add a small amount of water to achieve the desired consistency.
6. Pour the puree into a baby-safe bowl and let it cool to a safe temperature before serving.

Summary:
This Banana Orange Puree is a nutritious and delicious snack for babies aged 4-10 months. Bananas are rich in potassium and are easy on a baby’s digestive system, while oranges provide a good dose of vitamin C and help in strengthening the immune system.

Storing Options:
You can store any leftover puree in an airtight container in the refrigerator for up to 24 hours. Always check the stored puree for any signs of spoilage before feeding your baby.

Possible Side Effects/Allergies:
While bananas and oranges are generally safe for babies, always introduce new foods one at a time to monitor for any allergies. Oranges are citrus fruits and may cause a mild rash around the mouth in some sensitive babies due to their acidity. If your baby shows any signs of discomfort or allergic reaction, discontinue use and consult your pediatrician.