Well...
Seitan dough
Dry ingredients (mix these together first)
-4 desiliters of gluten flour
-2 desiliters of chickpea flour; a portion of this (but no more than half) can be soy flour, but it can be chickpea only as well, you might have to test it out what kind of mix you like the best
-spices to your own taste (I use garlic powder, paprika, chili, coriander, black pepper, ginger, garam masala), just don't be too skimpy with these or else it might be left a bit too tasteless , at least 1-1,5 teaspoons of all of these but if you like spicier you can probably use more. You can also use fresh garlic, chili & coriander but I feel garlic & chili work just as well as the fresh stuff as powders and coriander (& chili) works well dried
-1 tblsp vegetable stock powder
-2 tblsp nutritional yeast
Liquids
-2,5 desiliters of water
-0,5 desiliters soy sauce
-0,5 desiliters vegetable oil of your choice
Marinade (just mix all of these together)
-a couple of those small ~70 gram cans of tomato pure/paste
-3 tblsp oil
-1 tblsp soy sauce
-1 tblsp apple cider vinegar
-0,5 dl of water
-1 tblsp vegetable stock powder
-some onion powder
First mix the dry ingredients of the seitan together, then the liquids and then mix those all together. You can first use a spoon or something and once it's firmer, just use hand to mold it into a big log/lump. Cut that lump into smaller pieces (something like 10-15 pieces) and mold them into sausage-like form. Take some foil and put it onto an oven pan or another kind of oven-surviving deeper kitchen utility, then put the sausage pieces on the foil. Pour all of the marinade on & around the sausages (make sure the marinade doesn't flow off the foil) and wrap the foil around the sausages as air tight as possible (not too tight, though, since the sausages need some room to expand). Alternatively you can wrap each of the sausages into separate pieces of foil, but if one's as lazy as me, it's easier to just throw them inside one bigger piece of aluminum foil and be done with it.
Heat your oven to 175*C (or whatever that is in your American heathen systems) and cook the sausages in the oven for 1,5 hours. You might survive with 1 hour & 15 minutes but 1,5 hours should guarantee that they aren't left raw, especially if you make thicker sausages
Note: I'm not really sure how much this actually resembles "real" chorizo since I never ate it before abandoning meat, but this is a pretty good spicy seitan sausage that I've made using meat chorizo recipes & my knowledge of seitan making as a roadmap.