Preheat your oven to 400 degrees F. Line a rimmed pan with parchment paper. Use one 7 oz can of tomato paste and brush the paste evenly on the beef and marrow bones.
Roast the bones in the oven for 20-30 minutes. Don't allow them to get too black. Remove the pan and set aside.
In a medium dutch oven, combine the tallow, minced garlic, and diced onion. Saute until onions are clear.
To the dutch oven, add the tomatoes, 2 C. of water, the remaining 7 oz can of tomato paste, dried herbs, salt and pepper. Add the roasted beef & marrow bones as well as the beef fat drippings from the roasting pan.
Simmer the sauce for 2-3 hours on low/medium. Then remove the bones and set aside.. they can be used for bone broth (do not toss!)
Remove the pot from the heat. Use your immersion blender to blend the sauce until it's at your desired preference (smooth or semi-smooth). Pour into pint size, wide mouth Ball or Kerr jars.
Freeze for up to 3 months.