Coat the tomatoes, bell peppers and artichoke hearts lightly with oil, place on grill just away from the hottest spot. Turn occasionally with tongs to sear all surfaces. Remove to a dish to let cool. Reserve any juices that accumulate.
In a large saucepan, saute onion and garlic with butter over medium heat, stirring. In a food processor, small chop the grilled vegetables. In saucepan with onion/garlic mixture, add vegetable stock, cream, grilled vegetables, and cilantro. Bring to simmer, stir to heat evenly. Combine cornstarch and water in a small separate bowl. Slowly add to saucepan while stirring to combine. The sauce will thicken slightly in 1 to 2 minutes to desired consistency. Add more cornstarch or water if necessary.
Add salt, dash with pepper, to taste. Serve with suggested garnishes, if desired.
This recipe was provided by a chef, restaurant or culinary professional. It has not been tested for home use.