DIRECTIONS
Preheat oven to 450 degrees.
Toss tomatoes, onion, chili, and garlic with the olive oil.
Arrange mixture on a rimmed baking sheet and sprinkle with thyme.
Roast, shaking the pan periodically to ensure even cooking, until all vegetables are well charred, about 30 minutes.
Remove pan from oven and let vegetables cool to room temperature.
Put the charred vegetables in a food processor.
Add cilantro and mint, and process to a coarse puree.
With the motor running, drizzle in sesame oil, then add soy sauce, and puree until smooth.
Place lobster halves cut side up in a large baking dish or other container large enough to hold them in a single layer.
Spoon half of chili sauce over lobsters.
Cover loosely with plastic wrap and refrigerate for 1 hour.
Reserve remaining sauce.
When ready to cook lobster, preheat a gas grill or a ridged grill pan to medium or prepare a fire in a charcoal grill, letting the coals burn down until covered in white ash.
Oil the grill rack.
Lift lobster halves from marinade and turn them over, letting any excess marinade run off.
Put them cut side down on the grill, and cook for 5 minutes.
Use tongs to turn them over and grill, using a brush to baste meat with the butter, for another 5 minutes, or until meat turns opaque and begins to pull away from shell.
Put 1 lobster half on each plate and the remaining sauce in a bowl.
To serve, spoon remaining chili sauce over lobster.