Rinse the buckwheat groats thoroughly under cold water and let them drain.
In a large skillet or saucepan, heat the butter or oil over medium heat.
Add the chopped onion and cook for 5–7 minutes until soft and lightly golden.
Add garlic and mushrooms. Sauté until mushrooms are browned and most of the moisture has evaporated.
Stir in the buckwheat groats and toast them in the pan for 2–3 minutes to enhance their nutty flavor.
Pour in the broth. Add thyme, salt, and pepper. Stir well.
Bring the mixture to a light boil, then reduce heat to low. Cover with a lid and let simmer for about 15–20 minutes, or until the liquid is fully absorbed and the buckwheat is tender.
Fluff with a fork and let sit uncovered for a few minutes before serving.
Garnish with fresh parsley and serve warm.
Serving suggestions: Goes perfectly with a dollop of sour cream, pickles, or a fried egg on top.