Arrange the tomatoes, jalapenos, onions and garlic on the griddle and roast, turning several times, until blistered and slightly charred, 10 to 15 minutes. Remove the vegetables from the griddle and let cool slightly.
In the bowl of a food processor, combine the roasted vegetables, chipotle and adobo sauce and pulse until coarsely chopped. Transfer to a large bowl and stir in the cilantro and lemon juice. Season the salsa with salt and ground black pepper to taste.