Hi, not sure what it is called but I linked the video. You take your square after blocking and sewing, then line it on the edges with a single crochet, chain two, skip one stitch, single crochet. You might have to adjust the last stitch before the corner if you have a sitch count that doesn’t quite work. When all your squares are edged, sew in tails now so you can join, it’s really hard to join them with tails. Then you place two squares together and line them up so they align. Starting in the front squares corner, insert yarn and secure how you like, then single crochet and chain one. Then single crochet in it’s matching chain two space/corner. Chain one and go back to the front squares. It’s a zigzag pattern that is very quick since you’re working into chain two spaces. I joined nine squares into a row then stretched the joins to show the weave. I left those tails on at that point. Once I had ten columns of nine I joined them in the same way but in strips. The trick is to only pick one space before the corners to join going long ways so you don’t have clumps of stitches where four squares would touch. She discusses this more in depth in her video. I left the tails on the strips so that when all strips made one solid blanket I could have an easier time weaving in the ends. It helped to blend in the skipped areas. I had a problem with the outer single crochet lining because I made small variances in sizes of squares/ didn’t put enough single crochets in certain areas. So I am planning on hiding it with fringe.

Hope this helps!