Place oil, 3/4 poundtomatoes, sugar, and thyme in 8 x 8 x 2-inchmetal baking dish. Roast until tomatoesare very tender, about 2 1/2 hours. Coolcaramelized tomatoes in oil. DO AHEAD: Canbe made 2 days ahead; cover and chill. Bringto room temperature before continuing.
Using slotted spoon, transfer tomatoesto large bowl.
Transfer 1 cup oil fromtomatoes to medium bowl (reserve anyremaining oil for another use).
Add vinegarto oil in medium bowl; whisk to blend.Season dressing with salt and pepper.
Add 1 pound fresh tomatoes, cheese,and dressing to bowl with caramelizedtomatoes; toss gently. Top with greenonions and chervil.
Serve with toasts.
* San Simóncheese, a smoked cheeseshaped like a bell, is sold at natural foodsstores, specialty foods stores, and latienda.com. Smoked Gouda can be substituted.