In a large skillet or sauté pan, heat 1 tablespoon of the oil over medium-high heat. When it shimmers, add the onion and a pinch of salt and cook, stirring frequently, until translucent, about 5 minutes. Add the garlic and mushrooms and turn the heat to high; cook, stirring frequently, until the mushrooms have released their liquid and it has mostly evaporated, about 5 minutes. Scrape into the slow cooker.
Return the skillet to medium heat, add the remaining 1 tablespoon oil, then crumble in the drained tofu. Cook for 1 minute, then add the ancho chile powder, cumin, chipotle chile powder, and oregano, stir for 30 seconds, and scrape into the cooker. Pour ½ cup (120 ml) water into the hot skillet, scraping up any browned bits, then pour the liquid into the cooker. Stir in the tomatoes, beans, and 1 teaspoon salt. Cover and cook on low for 8 hours.
Season with tamari, if needed, then serve.