Roasted Tomato Soup

Balsamic vinegar is one of my top favorite ingredients to cook with. The recipe below is one of my perennial favorites. I don't like sweet tomato soup or tomato soup that tastes like spaghetti sauce but the tanginess of this soup makes it a big hit with me. I got this recipe from someone else so I don't know who the original creator is. I made a minor modification in the recipe: it originally called for 1/2 cup of olive oil divided (for tomato mixture and for cooking onion) and I found that to be too much and reduced it to 1/4 cup, sometimes less.

12 large, ripe tomatoes, about 4 lbs (2 kg) total or 3 large (28oz) cans whole tomatoes, drained.
1/4 cup extra virgin olive oil
1/4 cup balsamic vinegar
12 large garlic cloves, peeled but left whole
kosher salt and ground pepper
1 cup finely chopped yellow onion
2 cups water
1/2 to 1 cup lightly packed fresh basil leaves (based on how much basil you like)

1) Preheat the oven to 500 F (260 C)
2) If using fresh tomatoes: core the tomatoes and quarter them lengthwise. If using canned tomatoes: drain the juice and slice in half lengthwise. In a large bowl, mix the tomatoes, oil, vinegar, garlic, 1 teaspoon salt, and 1/2 teaspoon pepper. Spread the tomatoes on a nonreactive baking sheet (a glass casserole pan or stainless steel pan is fine). Roast the tomatoes in the oven until there are very dark spots, about 35-40 min. Remove from heat and let cool.
3) In large saucepan over medium heat, cook the onion in 1 tablespoon olive oil until very soft, 8-10 min, stirring occasionally. Raise the heat to high and add the roasted tomatoes and water. Bring to a simmer and adjust the heat to maintain the simmer, and cook 5 minutes. Season to taste with salt and pepper.
4) Remove from heat and let cool slightly. Put in the basil leaves and puree in the pot with an immersion blender (or work in batches with a blender). Wear an apron!

Eat with croutons, side of salad, or grilled cheese sandwiches. Yum!

Note: I tried this with basil leaves one time and omitted it the next time and we prefer this soup without the basil leaves. It's up to you. The recipe says to spread the tomatoes in the pan to roast but I dump the entire mixture in a pan with sides so as to cook in the balsamic vinegar. I did say balsamic vinegar is one of my favorite ingredients, right?