Set a 12 inch cast iron skillet over medium high heat and pour in the olive oil. Give it close to ninety seconds before adding anything else so it heats through fully. The oil is ready once it shimmers over the surface and moves easily around the pan when you tilt it.

Add the flour and stir constantly with a wooden spoon for close to two minutes. The mixture turns from pale white to a warm tan color as it cooks over the heat.

My roux went from tan to nearly black in about ten seconds once, right after I stepped away to answer the phone on a Tuesday. Pull the pan off the burner the second it smells sharp or burnt, and start over with fresh flour.

Pour in the thawed Bueno red chile puree along with 14 to 20 ounces of water, depending on the thickness you want. Whisk briskly for about a minute to knock out any lumps left from the roux.

Stir in the minced garlic, Mexican oregano, and salt. Bring the whole pot up to a boil over medium high heat, stirring every so often so nothing scorches on the bottom.

Drop the heat to low and let the sauce simmer uncovered for 20 to 25 minutes, stirring occasionally. It thickens slowly and turns a deeper brick red as the water cooks off.

The sauce is ready once it coats the back of a spoon and holds a clean line when a finger drags through it.

Stir in the scant teaspoon of sugar and simmer for another 5 minutes. Taste it, then adjust the salt one more time before pulling the skillet off the heat entirely.