Preheat the oven to 375F/190C
Slice the tops off the tomatoes and scoop out the flesh and seeds, next place the tomatoes into the baking dish with the tops resting at the side of them
Place the tomato flesh and seeds into a blender with the balsamic vinegar, Italian seasoning, 2 tbsp of olive oil and 1/2 tsp of sea salt and blend until smooth
Heat the remaining 1 Tbsp of olive oil into a frypan, add the chopped onion and fry until soft, add the minced garlic for a further 1-2 minutes
Add the ground beef and season with the remaining salt and pepper, cook until the beef is fully browned
Add the cauliflower rice and the tomato mixture
Bring to a boil then simmer for approximately 10 minutes stirring occasionally, simmer until the liquid has absorbed and the cauliflower rice is softened
Carefully using paper towel, remove any remaining juice inside the tomato shells, then spoon the meat and rice into the tomatoes, place the lids on top and cover with foil, bake for 30 minutes
Remove the foil and cook for a further 15-20 minutes or until the tomato shells are soft
Serve as a main option, side dish or store for snacks