Here is a Youtube tutorial on how to create this block with a paper foundation. You can also use a muslin foundation, as patski describes, in which case you leave the muslin in (with paper, you have to remove the paper before sandwiching).
https://www.youtube.com/watch?v=iZ02NM9-USw
Edit: In your photo, it looks as if the blocks were rectangular (either paper or muslin).
Edit #2: You can simply sew strips together and then trim into a block. However, it can be quite difficult to keep these blocks uniform because the strips are not stabilized. Using a foundation makes it very easy to use up scraps and also minimizes waste.