Slice tempeh into quarters (4 slices). Whisk together your favorite bbq sauce with ¼ cup water, and marinate tempeh in the mixture for 20 minutes in the fridge.
Toss together shredded cabbage and carrot in a bowl. Add minced garlic, cumin seeds, ground mustard, sea salt, ground black pepper, rice vinegar and hot water and combine until well mixed and the cabbage and carrot are submerged. Refrigerate until ready to assemble sandwiches.
Lay marinated tempeh slices onto a parchment lined baking sheet and bake for 20 minutes, flipping the slices half way through baking time and using extra marinade to baste them once or twice.
Prepare the baguette/buns by spreading 1 tablespoon of vegan mayonnaise on the inside of each side of the bun.
Shake excess liquid off of the pickled cabbage and carrot, and place a small handful on the bottom bun. Place a couple slices of baked tempeh on top and add cucumber, cilantro, and pickled jalapénos.