Place the tomatoes, garlic, scallions, cilantro, lime juice, and Serrano slices in the bowl of a food processor fitted with a metal blade. Pulse until smooth. Season to taste with salt and pepper.
Chill in the refrigerator until ready to serve. Keeps up to 4 days, refrigerated.
Notes
We enjoy this salsa with chips but also on tacos, in burritos, or atop chili.