Cut the snapper fillets lengthwise into 2 or 3 strips, then finely slice across the grain. Set aside.
Combine the tomatoes, onion and jalapeños in a small bowl. Set aside.
Melt the butter in a large sauté pan over medium-high heat. Add the fish and sauté for about 3 minutes, or until it turns white. Add the tomato mixture and cook, stirring, stir for 2 to 3 minutes longer. Stir in the lime juice and cilantro. Season with salt.
Serve with warm corn tortillas or corn chips.
Makes: 4 to 6