No need to add milk to pureed food.
You can prepare any fruit or veg in a blender (plain, nothing added), freeze it in ice cube trays, remove to freezer bags, thaw and then serve.
I have served steamed and pureed prunes, butternut squash, carrots, peas, green beans, sweet potato, aubergine, apricots, courgettes, lentils, as well as steamed apples, to babies, with nothing added.
Have also fed them mangoes and peaches from frozen (thawed and then blenderised), spinach (done in microwave), avocados (these can be frozen raw in slices and then mashed when thawed; they have lots of good fats for babies), cherries and blueberries (thawed then blenderised). Bananas can also be mashed and frozen in ice cube trays.
Moved up to loin of pork and chicken breast, also pureed, and egg yolk (frozen as they came out of the whites, like yellow marbles). In order to make pureeing easier/produce less dense puree, I added some of the steaming water to the blender.
The taste of home prepared food was much nicer than food from jars I found.
You could add a little milk to the baby porridge, but it's not necessary.