Chop sweet potato and carrots into small pieces. (Chopped sweet potato and chopped carrots should be of equal quantity. So you can decide how many carrots you need depending on the size of the carrots.)
Chop the onion finely. (Onion shouldn't overpower the flavor of the soup. So it's better to use a small onion, that too half.)
Coarsely grind the cinnamon, cumin seeds, cloves, and peppercorns using a pestle. Decide on the number of peppercorns and cloves depending on your child's age. If you haven't introduced spices in your baby's diet yet, you can add the spices without grinding them. You can later remove them from the mixture before blending it in a blender/mixer. You won't be able to remove the cumin seeds of course.
Heat a small pressure cooker and add olive oil.
Add the ground spices, sauté for 10-15 seconds, and then add chopped onion.
Sauté till the onion turns soft. (This won't take more than 4-5 minutes since we're using very little onion.)
Add chopped sweet potato and carrots, and sauté for a minute.
Add salt and give the mixture a good stir. (Note: It is recommended to avoid adding salt in babies' food till they turn one. However, in my case I found that Devansh just wouldn't eat his food without salt. Hence, I started adding little bit of salt in his food. You can decide whether you want to add salt or not after talking to your child's pediatrician.)
Add one cup water and then cover the lid of the cooker.
Cook the mixture on medium-high heat till the first whistle, and then lower the flame.
Turn off heat after the second whistle.
Allow the mixture to cool, and then blend it to a smooth paste in a mixer. (If you're not keen on adding spices in your baby's diet, you can remove the peppercorns, cinnamon, and cloves before blending the mixture. Cumin seeds should be fine but they need to powdered finely, so it's better to use jeera powder instead of whole cumin seeds. As I've mentioned above, I had started adding powdered cumin seeds in Devansh's food since he was 6-7 months old. Consult your child's pediatrician if you are not sure.)
Heat the soup before serving it. (I wanted to feed Devansh thick soup so I didn't add any water. If you want, you can add some water or even milk to the soup at the time of heating it again.)