Combine sour cream, lime zest and 1 tbls juice with ¼ cup cilantro and cumin in a bowl
Brush tomatoes and jalapeno with oil and season with salt and pepper. Grill vegetables over hot fire until charred and tender about 2 minutes per side. Remove skin from tomatoes and process in a blender with the jalapeno, remaining 1 tbls lime juice and ¼ cup cilantro until smooth. Transfer to a bowl and season with salt and pepper.
Brush fish with oil and season with salt and pepper. Grill fish over a hot fire, until lightly charred and just cooked through. Transfer to a plate and tent. Grill tortillas briefly over the fire
Spread each tortilla with crema, add fish and salsa and serve immediately. Pass crema at table