Choose your substitute based on dish needs: tempeh or tofu for protein and chew, jackfruit for pulled texture, mushrooms for moisture and umami, chickpea flour for patties.
Prepare each substitute accordingly: press tofu to remove moisture, steam tempeh, drain and rinse jackfruit, slice mushrooms thick, or mix chickpea flour with water and spices.
Use equal weight or specified volume ratios to replace seitan in recipes (except jackfruit which requires 1.5x volume).
Cook or simmer your substitute as needed: sauté, grill, or simmer jackfruit for 15-20 minutes; bake chickpea flour patties until firm and golden.
Check final texture and flavor; adjust seasoning to balance earthiness or moisture differences compared to seitan.