Start by coring your tomatoes and placing them in two 9x13 glass baking pans. Squeeze in the quartered onions and garlic. Drizzle olive oil on top and sprinkle with Kosher salt. Use more salt than you think you should!
Roast at 425 degrees for 30 to 40 minutes or when the tomatoes have broken down and are starting to get a nice char.
Set aside to cool. I then used tongs and plucked up the tomatoes and threw them in the food processor to blend along with the fresh basil. Be sure to reserve the tomato liquid from the roasting! Add to the completed sauce to reach the desired consistency. Or use the liquid for something else. I made minestrone soup and dumped some of the liquid in for flavor...yum!
The sauce is flavorful not to mention pretty with the flecks of basil. I never added the tomato paste the recipe calls for and don't think it's lacking. I froze 3 cups of sauce in 1-quart bags. It freezes well and retains that taste of Summer!
Roasted Marinara Sauce
(The amounts listed in this recipe are just a good place to start. Adjust the ingredients to suit your tastes.)
8 c. cherry tomatoes or 24 medium tomatoes
2 medium onions, quartered
8-10 garlic cloves, peeled
1-3 cans tomato paste, optional
Wash and stem the cherry tomatoes or wash and core the whole tomatoes. Split them evenly, in a single layer, between 2 9×13″ baking dishes. The larger tomatoes can be left whole; they will break down during the roasting process. Toss the quartered onions and peeled garlic cloves evenly between the two pans. Drizzle with olive oil and season generously with salt.
Roast at 425 for 30-40 minutes. The timing isn’t an exact science. The combination will smell incredibly fragrant, and the tomatoes and onions will look wrinkled, roasted, and slightly charred. For a thicker sauce, cook longer and stir occasionally to keep from burning. Remove the pans from the oven and set on the counter to cool for 10-15 minutes.
Place a large colander inside a large bowl and dump the pans into the colander to strain out the juice. Set the juice aside.
Scoop the tomato mixture into the bowl of a blender or food processor; add the basil leaves. Puree until it reaches the desired consistency. Dump the pureed tomato sauce into the reserved juice and stir until thoroughly combined. Season with additional salt, if needed. (You could also add tomato paste if you desire a thicker sauce.)
Serve immediately as pasta or pizza sauce or freeze in plastic containers or bags for later use.