This has been my go-to method for sauce these past few years. I simply roast the tomatoes, then puree them and stick them in the freezer. If I want to turn it into soup, then I can add chicken broth before or after freezing. I can make a small batch or large batch, depending on how many tomatoes are ready from my garden. So easy, and sooooo good!
Source: marthastewart.com
4 lbs plum tomatoes, halved
2 medium yellow onions, diced
3 garlic cloves, smashed and peeled
1/4 c. extra-virgin olive oil, plus more for drizzling
sea salt and ground pepper
Preheat oven to 450 degrees. Toss together tomatoes, onions, garlic and oil; season with salt and pepper. Arrange in a single layer on a rimmed baking sheet and roast until tomatoes are deep brown in spots and onions are soft, approximately 45 minutes.
For sauce, simply puree in blender.
To make Roasted Tomato and Tarragon Soup from this mixture:
Transfer vegetables and all juices to a large pot. Add 4 c. chicken broth and bring to a rapid simmer. Cook until slightly reduced, about 25 minutes.
Puree in blender until smooth.
Stir in 2 T. fresh chopped tarragon, and season with salt and pepper.
If necessary, thin with additional chicken broth, and serve with a drizzle of olive oil.
