Pescado con Salsa Fria de Nuez (Fish with Cold Walnut Sauce)

Blend the chiles, onions, garlic, cheese, and half-and-half in a blender or food processor until the mix resembles a thick mayonnaise. Continue blending and add more half-and-half until the mix is like thick cream. Season with slat and pepper and refrigerate until ready. Makes 3 cups of sauce.
Rinse the fish under cold running water and pat dry. Season generously with salt and pepper, then dredge in flour, shaking off the excess. Melt butter and oil in a large skillet, then saute the fish over medium heat about 4 minutes per side, until the flesh is no longer opaque.

Serve immediately with the cold nut sauce. Garnish with olives or capers.