Noun, する verb, and の adjective
じすい
忙しいけど、ちゃんと自炊してるよ。実際、昨日の夜はラタトゥイユっていう野菜の煮込み料理を作ったよ。
I’ve been busy, but I do cook for myself. In fact, last night I made a stewed vegetable dish called ratatouille.
A self cook is cooking for oneself. Better break out the TV tray.
This is a jukugo word that uses the on'yomi readings of the kanji. You should be able to read this on your own.