The marinade and pan sauce for this dinner are packed with umami flavors. They work together to elevate seared tofu, mushrooms and mashed sweet potatoes into a meal that is restaurant-worthy.
Place chopped sweet potatoes into a stock pot and cover with cold water. Bring to a boil, and then simmer until you can easily insert a knife through the potatoes, ~6 to 10 minutes. When sweet potatoes are done, drain and let steam for ~5 minutes so some of the moisture evaporates.
While sweet potatoes are cooking, heat a saute pan over medium-high heat. Add cooking oil and then tofu to heated oil. Sear on both sides for 3 minutes. Remove and set aside.
Lower heat to medium and add mushrooms, thyme sprigs (the portion for the tofu), white wine and stock, scraping up any brown bits that may have formed on the pan. (There will be some steaming action, so be careful!) Cover and cook for another 3 to 4 minutes.
Add cornstarch mixture to the pan. Bring to a simmer and let sauce cook until it's thickened. Turn off heat, and add lemon juice, parsley, and season to taste with salt and pepper. Add tofu back to the pan and spoon mushroom sauce over top.
Mash sweet potatoes with yogurt, starting with less and adding more as needed. Season to taste with salt.
Serve tofu over mashed sweet potatoes with mushroom sauce over top. Enjoy!