Oven-Roasted Tomato Sauce

The bounty of late summer produce comes with shortening days, cooler evenings, and the urge to stash away provisions for the winter.

With so much to do in the late summer, I gravitate towards the simplest and quickest methods for preserving food - and always with top flavour in mind.

That’s one reason I like this tomato sauce.

There’s minimal hands-on time involved, and the finished sauce is delectable.

Not to mention — while the sauce is roasting, the house is filled with a most luscious aroma!


As with many great dishes, this is more of a process than a recipe… the quantities of the ingredients are easily adjusted to match whatever volume of tomatoes you have to preserve - whether a 3L basket, or a bushel.


Fresh tomatoes (eg, 2 x 3L baskets); preferably Roma or other paste tomato, but this can easily be made with heirloom or slicing tomatoes as well - or even cherry tomatoes

Cooking onion, sliced thinly

Garlic, sliced or minced (2 - 6 cloves per pan, depending on your tastes)

Basil, several sprigs

Sea salt & pepper

Olive oil (approximately 2 - 4 Tbsp per pan)


  1. Choose a deep roasting pan (not a baking sheet) that will be at least 3/4 filled with the volume of tomatoes you’ll be processing

  2. Prepare the tomatoes by removing the cores and either chopping the tomatoes or slicing them into quarters or eighths

  3. Layer about half of the tomatoes in the roasting pan

  4. Scatter the sliced onion, garlic, and sprigs of basil evenly over the tomatoes

  5. Sprinkle salt and pepper over everything

  6. Fill the pan with the remainder of the sliced tomatoes, being sure that the pan is not heaped. If using juicy tomatoes, drain off the surplus liquid.

  7. Sprinkle salt and pepper over the tomatoes, then drizzle on a generous portion of olive oil

  8. Roast the tomatoes at 250 - 300F for 3 - 8 hours. They will take longer to roast at a lower temperature (obviously), but lower temperatures can bring out sweeter, richer tones.
    The reason for such a wide range of cooking times is that it really depends on the type of tomatoes you’re using, and how deep the tomatoes are in the roasting pan. You’ll know they’re done when much of the liquid has evaporated, and some of the top bits of tomato are starting to brown.

  9. Stir the tomatoes (and remove any large basil stems), then cool them, then pack into freezer containers - and save the fragrant, delicious flavours of summer for the winter!

  10. * If desired, the tomato sauce can be processed through a food mill to remove the skins and seeds… after cooling slightly, and before freezing. If you’re pressed for time, this step can be skipped. The sauce will have more flavour if the tomatoes are cooked with the skins on.

This sauce is very versatile. Puree it for a base for tomato soup (just add cream & adjust the seasoning!), use it as a pasta sauce, lasagna sauce, pizza topping, add to stews or casseroles, etc.