Grilled Swordfish Tacos with Molcajete Salsa - Rick Bayless

Ingredients

• 1 1/2 pounds (5 to 6 medium round or 7 to 8 plum) ripe tomatoes
• Fresh chiles to taste ( I like 2 jalapeños, or 4 serranos or 1 habanero), stemmed
• 3 garlic cloves , unpeeled
• 1/2 medium white onion, chopped
• About 1/3 cup (loosely packed) roughly chopped cilantro
• Oil for coating the fish
• Salt
• Four 5- to 6-ounce swordfish steaks (3/4 to 1 inch thick is best)
• 12 warm corn tortillas
• 1 cup baby arugula (optional)