Heat a stove top and ovenproof casserole dish or a frying pan over a medium high heat. Add a few tablespoons olive oil and cook tofu until golden brown all over.
Remove tofu and add onion with a little more oil if it looks dry. Cover and cook onion stirring occasionally until the onion is lovely and soft and slightly golden. Add carrots, celery, garlic and cook for a few minutes. Add mushrooms in batches, stirring until they cook down and make space for the rest.
When all the mushies are in, add the browned tofu, thyme, tomatoes, butter and 2 tablespoons of the soy sauce. Top with 3 cups water. Bring to a simmer on the stove top then pop in the oven. Cook, uncovered for 2 ? 2 1/2 hours, stirring every half an hour or so. It?s ready when the mushies are nice and tender and the liquid has reduced to a lovely saucy consistency.
Taste and season with a little extra soy, salt and pepper if needed.
Prepare pasta according to directions and serve ragout over hot pasta.