I recommend fruits puree as a starter. Apple, avocado, banana and pears are common first fruits introduced to babies. You steam those then blend or mash it. Add some breastmilk to make it a bit watery.
Since baby's gut is still immature, you can delay rice cereal/porridge. It is not a must to start with cereal because your baby's main food will still be your milk at least till he is 1 y/o.
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