Heat a large-rimmed skillet, pot, or dutch oven (as large as possible to give room for browning) over medium heat. Once hot, add oil (or water) and onion and sauté for 4-5 minutes until translucent and soft, stirring frequently. If using water, add more water as needed as it evaporates quickly.
Add mushrooms and stir. Sauté for 2 minutes more. Then add shredded tempeh and garlic and stir (if your pan is small, do this in 2 batches so the tempeh has room to brown*). Then add coconut aminos, fennel seeds, and red pepper flake. Sauté for 4-5 minutes (or up to 10 minutes), stirring frequently, until everything is golden brown. Turn down heat if browning too quickly.
Add wine (optional), stir, and cook for 1 minute. Then add crushed tomatoes, tomato paste, oregano, vegan parmesan, and sweetener. Thin with water if needed (we added about 1/4 cup / 60 ml). Stir to combine and simmer for 10 minutes.
Taste and adjust flavors as needed, adding more coconut aminos or salt for saltiness, red pepper flake for spice, oregano for herbal flavor, tomato paste for depth of flavor, or vegan parmesan for cheesy flavor.
Serve with your favorite pasta or pasta alternative, like spaghetti squash, penne, or zucchini or carrot noodles and garnish with fresh basil (optional)!
Cooled leftovers will keep covered in the refrigerator up to 5 days, or in the freezer up to 1 month. Reheat in a saucepan or microwave until hot, adding a little water as needed to rehydrate.
*It’s important to use a pan large enough that the tempeh has room to sauté. Add a bit more oil as needed to deglaze the pan and ensure the tempeh is browning up nicely! *Nutrition information is a rough estimate calculated with lesser amount of vegan parmesan cheese and maple syrup and without the optional ingredients.