Preheat the oven to 350 °F.
Drain liquid from the can of jackfruit and finely dice jackfruit pieces (core, seeds and all). Set aside.
In a large bowl, mix together the dry ingredients: 2 C gluten flour, ¼ C nutritional yeast, 1 tsp garlic powder, 1 tsp onion powder, 1 tsp smoked paprika, ½ tsp celery seed, ½ tsp Herbamare seasoning, pepper to taste.
In a separate bowl, whisk together the wet ingredients: 3 tbsp tahini, 3 tbsp soy sauce, 2 tbsp oil, 2 tbsp ketchup, 1 tbsp apple cider vinegar, 1 C vegetable broth. The tahini won’t fully mix in (there will be flecks of tahini and oil throughout, which is fine).
Pour wet ingredients into dry and mix until a ball of dough forms. Stir the ingredients with a spoon. Use your hand to finish mixing when it becomes too doughy to stir.
Add 1 C chopped jackfruit into the mixture and knead until it’s well incorporated throughout. You want the jackfruit as dispersed as possible (no clumps of jackfruit in any one spot).
Dump the dough onto a large piece of tinfoil and shape into a flat rectangle. It can be however thick you like but 2-3 cm (around 1 inch) works well.
Carefully wrap the dough with the tinfoil as tightly as possible. Take a second sheet of tinfoil and wrap the dough a second time, placing the open edge of the tinfoil down onto the center of the new sheet to create a good seal.
Place the tinfoil-wrapped dough onto a baking tray and bake for 50 minutes.
Once out of the oven, allow to cool completely. Carefully unwrap the cooked seitan and place in the fridge for fast cooling. It’s helpful to allow this to sit in the fridge for a few hours or overnight if you have the time.
When ready to barbecue, make careful slices across the cooked seitan, halfway down and about 2 cm/ 1 inch apart. Then, brush BBQ sauce across the top of the seitan and work it down into these slices.
Heat the BBQ to about 500 °F. I use 3 burners on my barbecue (the 2 on the outer edge set to medium-high and the center one, which the seitan will be directly over, as low as possible).
Place the seitan on the barbecue, sauce side down. Brush the opposite side with BBQ sauce. Allow to cook for 5 minutes then flip. Sauce the side that’s now face up, cook for 5 minutes then flip. Repeat again so both sides are sauced and grilled twice.
Remove from the barbecue and slice into individual “ribs” for serving.