Cast on 48 stitches on provisional crochet cast-on.

The pattern (recipe) I used is:
https://www.abeeinthebonnet.com/blog/my-vanilla-sock-recipe/

For one of the heel flaps, I used a slip stitch pattern from YouTube. Basically on the RS, you knit, slip as if to knit, etc. On the WS, purl all stitches.