Cut the baguette into thirds or three 6″ pieces. Then slice them open lengthwise to use for the banh mi. (Toast if desired).
Place the sriracha aioli down on the interior of the bread in a zig-zag pattern out of a squeeze bottle; then spread the sauce down to cover the cut side of the bread from end-to-end with an inverted spatula.
Meanwhile, add the pulled short rib and the pho broth to a small saucepan and bring to a simmer.
Remove the short rib from the broth and place it down on the bottom piece of bread.
Add the remainder of the broth to a small soup cup and then onto a plate.
Add the cilantro gremolata on top of the short rib, followed by another line of the aioli.
Add the pickles on top of that, followed by the top of the bread.
Serve the beef banh sandwich with the pho on the side.