Heat 1 tablespoon (15 ml / 0.5 fl oz) of olive oil in a large skillet over medium heat.
Add the seitan slices, season with salt and pepper, and cook for 3 to 5 minutes, turning once, until golden brown on both sides.
Transfer the seitan to a plate and set aside.
In the same skillet, heat the remaining 2 tablespoons (30 ml / 1 fl oz) of oil over medium heat.
Add the chopped red onions and sliced radicchio.
Cover the skillet and cook for about 5 minutes, until the vegetables have softened.
Stir in the water or vegetable broth, tamari, and dried thyme.
Season with additional black pepper to taste.
Return the browned seitan to the skillet, nestling it amongst the vegetables.
Cover and simmer for about 10 minutes, allowing the flavors to meld and the radicchio to become tender.
If excess liquid remains, remove the lid, increase the heat to medium-high, and cook for another minute or two until the sauce has reduced slightly.
Taste and adjust seasoning. Be cautious adding salt, as the tamari and broth will have concentrated.
Serve immediately over a bed of quinoa or brown rice.
Don't overcrowd the pan when browning the seitan.
Work in batches if necessary to ensure each slice gets a beautiful, crispy crust.
