Heat the olive oil in a large pot. Add onions and cook for 2-3 minutes. Add garlic and saute for another minute. Add the rest of the veggies (carrots, celery, zucchini, and bell pepper) and give it a little mix.
Add the strained tomatoes and vegetable stock and stir to combine. Add the tomato puree, italian herbs, and paprika, and bring to a boil.
Reduce heat to a simmer and cook for about 20 minutes, or until the veggies are soft. Stir occasionally so the vegetables don’t stick to the bottom of the pot. Add the basil at the end.
Remove from heat and use a blender to attain the desired consistency.
Serve immediately, or let cool and can/jar or freeze sauce.