3 dried guajillo chiles, seeded and torn into flat pieces
3 garlic cloves, unpeeled
1/214.5-ounce can diced tomato (preferably fire-roasted)
1 pound (8 medium) nopales cactus paddles
3T. olive or vegetable oil
1 large white onion, sliced 1/4-inch thick
Salt
A little sugar, if necessary
1 cup (4 oz.)crumbled Mexican queso fresco or other fresh cheese such as feta or goat cheese
A big handful of cilantro leaves

Prepare the guajillo chile base. Heat a medium (10-inch) skillet over medium. Toast the chiles by using a metal spatula to press them against the hot surface for a few seconds, until very aromatic, then flipping and pressing the other side. Roast the unpeeled garlic, turning from time to time, until soft and blotchy-black in spots, about 15 minutes. Cool and peel off the papery skin. Break the chiles into smaller pieces and combine in a blender jar with the garlic and the undrained can of tomatoes. Blend until smooth—this will take a minute or so because of the tough chile skins. Clean and cut the cactus. Holding a paddle with a pair of tongs, trim off the edge that outlines the paddle, including the blunt end where the paddle was severed from the plant. Slice or scrape off the spiny nodes from both sides of the paddle. When all paddles are cleaned, cut them into squares that are a little larger than ½ inch. Prepare the dish. In a large (4-quart) saucepan, heat the oil over medium. Add the onion and cook, stirring regularly, until richly browned, about 10 minutes. Add the cactus, cover the pan and cook 5 minutes. Uncover, raise the heat to medium-high and cook, stirring frequently, until all of the cactus’s sticky stuff has evaporated and you hear the cactus sizzling in the oil. Immediately, set a medium-mesh strainer over the pan, pour in the chile mixture and press it through. Stir everything together and let it cook until the chile mixture has thickened to the consistency of tomato paste. Stir in ½ cup water, reduce the heat to medium-low and simmer 20 minutes. Taste and season with salt (usually about 1 tsp.) and a little sugar if necessary to balance the chile’s natural astringency. Serving. Serve the warm mixture with the fresh cheese, cilantro and warm tortillas if you want to enjoy the dish as a filling for soft tacos.