Preheat oven to 350. Line a 13" by 5" loaf pan with foil and spray with oil cooking spray. Saute onions in butter and oil on medium heat for two minutes and then add the garlic and mushrooms and saute for another 3-5 minutes. Add the mushroom onion mixture to a larger mixing bowl. Add the herbs through the flax meal in the list and mix well. Then add the beef and breadcrumbs and mix well with your hands. Spoon meat mixture into loaf pan and smooth to even distribution. Bake for about 45 minutes or until the meat thermometer reads 165.
While the meatloaf is cooking, make the balsamic glaze. In a non-stick pan heat vinegar, water and sugar on a medium low heat. Allow the sauce to thicken to syrup like consistency. Taste and add more vinegar or sugar to your liking. Add the finely chopped tomatoes and set aside. When the meatloaf reaches 165 degrees spread half of the glaze on top of the loaf and return it to the oven for about 8 minutes. Remove loaf and let it rest for about 5-10 minutes before slicing. Drizzle a little glaze on each serving and serve with a tossed salad.