leathercraft

I am having an idea for a bag and I believe I have seen this technique somewhere before. I just have no idea what it’s called and hence have a hard time finding a video or instructions.

Essentially I want a round corner the comes out a bit and then the gusset over the two sides. I believe I have seen an approach where you cut a side piece with rounded corners and then cut perpendicular into the middle of the corner. Then sew that cut and turn over. The corner sticks out essentially and the side is then attached to a long piece that runs from one side around as bottom and up on the other side.

I am not sure if I am explaining this well enough to ID. I will try to find a pic.