Scale but don't skin the walleye and pick a 3-3 1/2-pounder. Salt and pepper the fish. Mix the minced onions with soft butter and spread inside and outside the fish. Lay the bacon strips on the bottom of a shallow baking dish and lay in the fish. In a bowl mix the sour cream, thyme, grated cheese, bread crumbs, and lemon juice and spread the mixture over the fish. Bake at 325 degrees for about 30 minutes. Serve with tossed salad and baked potato.