To make the pickled vegetables: Thinly slice the cabbage and measure out 2 cups. Thinly slice the onion and cucumber. Place the cabbage, onion and cucumber in a bowl and stir together with the white wine vinegar, rice vinegar, sugar, and kosher salt. Allow to stand at room temperature while you make the hummus.
To prepare the sandwich: Peel the carrot into ribbons. If using, thinly slice the jalapeno pepper. Tear the leaves from the cilantro. Slice the baguettes in half.
To serve: take the bottom baguette piece and pull out some of the soft bread to make a well. (This helps to keep the sandwich together while eating.) Spread the well with hummus, then top with the pickled veggies. Add carrot ribbons, sliced jalapenos (if using) and cilantro. Spread the top baguette with mayonnaise and serve.