From apples we've moved on to bananas. They are probably one of the easiest first foods since there is no cooking involved. You just mush up a banana until it's a consistency you like. Two bananas yielded one ice cube tray for me.
I then mixed the banana with some formula and baby rice to get it to a thickness that Blondie Boy would like. He prefers a somewhat thin, yogurt like texture to his food. I was worried that it turned brown, but I've been assured that it's absolutely fine and not to worry. Your frozen banana cubes will go brown, too.
He ended up getting covered in banana, it was definitely the messiest food so far, but the next few times weren't as messy as below. NotBlondeHusband was convinced Blondie Boy would hate bananas since he does (and did as a baby as well), but he's had them three nights now and was diving at the spoon tonight, so I suspect he likes them!