Fire Roasted Tomato Chipotle Salsa

Grrrrrgh!
Course : Salsas
From: HungryMonster.com
Serves: 1
 

Ingredients:

1 tablespoon virgin olive oil
1/2 medium onion -- (chopped)
1 pound blackened Roma tomatoes
4 teaspoons garlic
1/2 cup minced fresh cilantro leaves
4 medium chopped chipotle chilies en adobo
1 pound Roma tomatoes
1/4 cup virgin olive oil
1/4 cup red wine vinegar
1 tablespoon salt
1 teaspoon sugar
 

Preparation:

To prepare Fire Roasted Tomato Chipotle Salsa, in sauté pan over medium heat, place 1 tablespoon virgin olive oil. Add 1/2 onion (chopped) and sauté until caramelized, about 10 minutes. In food processor or blender, place onion, 1 pound blackened Roma tomatoes, and 4 teaspoons finely minced roasted garlic. Pulse until finely chopped but not pureed. Add 1/2 cup minced fresh cilantro leaves and 4 chopped chipotle chilies en adobo, pulse to mix. Peel, seed and chop 1 pound Roma tomatoes and add to mixture with 1/4 cup virgin olive oil, 1/4 cup red wine vinegar, 1 tablespoon salt and 1 teaspoon sugar. Obviously this recipe intrigues, what with the chipotle ingredient. I also can substitute a tablespoon of Balsamic Vinegar for some of the red wine vinegar. I can use fresh parsley if the IGA doesn't have fresh cilantro. We have available some cylindrical tomatoes about 1.5 in. D by 3.5 in. L, and I will call those Roma. My question is, how do you blacken a tomato? I could put 'em in the kitchen oven broiler I reckon. Spray with oil? Burn 'em till they blister? What is the point, surely this has to make some fundamental change to 'em that must be desirable. I guess I could also roast the garlic at the same ti