Place fabrics wrong sides together, pin and sew down with your normal seam allowance (I used a 1/2" allowance)

Lay the fabrics flat and open the seam up then press with your iron.

Fold the right side of the seam in half and press.

Fold both fabrics to the left and trim the right side of the seam, all the way along the fold you just created.

Lay fabrics flat again and fold the left side seam in half, then press.

Push the right side seam towards the left and press it with your iron so that it lays flat under the left side seam.

Fold the entire seam to the right and press. Now all raw edges are enclosed and you only have one more step to do.

Run an edge stitch along the opened edge on the right and you're done! Using a felling presser foot is helpful but not necessary.