Salsa a la Huancaína

Method

1. saute7 min
   medium heat, oil + fresh ají + onion + garlic, softened without deep browning
   Cook the fresh ají amarillo, onion and garlic until softened and aromatic. The goal is to take the raw edge off the chile and alliums while preserving the ají's bright fruitiness and color. If using prepared ají paste instead, warm it in the oil for only a minute or two; it has already been processed and does not need the same softening step.
2. rest3 min
   sautéed mixture cooled until no longer fiercely hot
   Let the chile mixture cool briefly before it meets the cheese. Blending very hot oil and dairy is both a splash hazard and an easy way to push the cheese toward a greasy texture before the sauce has emulsified.
3. mix5 min
   blender; cheese + chile mixture + half the milk first, then milk and crackers in stages
   Blend queso fresco with the ají mixture and half the evaporated milk until smooth. Add the remaining milk gradually, then add soda crackers one at a time until the sauce is creamy and pourable but thick enough to coat a spoon. The researched recipes disagree on exact cracker and milk amounts because cheese moisture varies; texture is the correct endpoint, not a blind average.
4. season3 min
   room temperature; taste before adding all the salt
   Taste and season with salt only after blending. Queso fresco varies in salinity, and the crackers contribute some salt too. The finished sauce should taste first of fruity ají amarillo and fresh cheese, with enough richness to coat potatoes or vegetables but enough looseness to pour rather than sit like a paste.