Set food processor with dough attachment. Add all ingredients to food processor and blitz for about 10 seconds to combine. With spatula, scrape down sides, then blitz again for about 1 minute or until sticky mixture forms with long stringy texture, almost like elastic. See Notes
Let dough rest for 10 minutes, then blitz again for about 15 seconds only. Add to work surface dusted with vital wheat protein, then cut dough into 4 equal pieces.
For Loaf
Place dough in center of 4x12-inch piece of foil, fold short sides of foil over loaf securely but keeping folds loose allowing dough to expand.
Place loaf in steamer basket in pot, cover, and steam for 30 minutes. Once cooked, carefully remove loaf from steamer, and allow dough to cool down to touch before chilling in fridge.
For Strips
Follow instructions for loaf, then slice cooled loaf into strips of preferred size.
For Shredded
Follow instructions for loaf, then shred cooled loaf by hand by pulling shreds of preferred size.
For Bites/Nuggets
Tear off bite sizes of dough, then place in steamer basket in pot in 1 single layer. Cover pot, and steam for 10 minutes. Once time is up, remove steamer basket immediately from pot, let seitan bites cool slightly for a couple of minutes, then separate bites if pieces of dough have expanded and started touching. Not that seitan bites will expand when steaming, but shouldn't be hard to pull apart from each other once cooled.
Store seitan loaf, strips, shreds or bites in fridge sealed in plastic bad or airtight container for up to 2 weeks. You can also freeze seitan by adding it to freezer-safe container, letting out as much air as possible.
Recipe Notes
The stringy texture is gluten and what makes seitan taste meat-like, so continue processing mixture til you see it. You can also hand knead dough just like bread by transferring to flat work surface dusted with vital wheat gluten, and kneading dough back and forth with hands for a 1 to 2 minutes.