Pre-heat the oven to 450F / 220C

Slice the Roama tomatoes long ways and place them on a baking rack

Cube the onion and piece it out onto the baking sheet

Make a small 1 cup sized bowl with Aluminum foil

Open the head of garlic by slicing the top, exposing the tops of the cloves, and place it in the foil cup

Drizzle and baste olive oil on all tomatoes and onions and pour some down the middle of the garlic head.

Roast the tray in the oven until the tomatoes are well charred (about 10 to 15m.)

Once roasted pull the tray from the oven and let cool for about 10 m.

Once cooled a bit, place the tomatoes and onion in a food processor.

Pull the Cilantro leaves from the stems and add them to the food processor.

Pull about 4 to 6 cloves of roasted garlic from the head and squeeze the garlic out of it's skin into the food processor.

Add 5 slices of jarred Jalapenos to the food processor (I would have roasted fresh jalapenos with the tomatoes, but they are not readily available where I live.)

Pulse in food processor until desired texture. Add salt and pepper to taste

Store in the refrigerator overnight for the flavors to marry.