Salsa is one of those condiments people just automatically think to buy at the store, but everyone should know that it's fairly easy — and healthier — to make your own at home. Rick Bayless' is described as mellow, but can be spiced up with the addition of more chiles or red pepper flakes. It goes great on top of his Swiss Chard Tacos.
Heat the broiler to high. Pull the steams off the dried chiles, tear them open, and shake out the seeds. Place in a bowl, cover with hot tap water, and lay a plate on top to keep them submerged.
Lay the whole tomatoes on a broiler pan or baking sheet. Set as close to the broiler as possible and broil until darkly roasted and blacked in spots, about 6 minutes. With a pair of tongs, flip over the tomatoes and roast them until they are cooked through, about another 6 minutes. Set aside to cool.
Turn the oven down to 425 degrees. Separate the onion rings and combine with the garlic on a baking sheet. Cook in the oven until the onions are soft and beautifully roasted, adn the garlic is soft and browned in spots, about 15 minutes. Cool to room temperature.
If you're not inclined toward rustic textures in your salsa, pull off the peels from the cooled tomatoes and cut out the "cores" where the steams were attached. By now, the chiles should be soft. Drain the chiles and combine with the tomatoes and their juice in a blender. Process to a rather smooth purée — chile skins are tough, so careful to make sure you've chopped them enough. Scrap 2/3 of the purée into a large bowl. Roughly chop the onion-garlic mixture, then add it to the blender and pulse repeatedly until all is finely chopped. Scrape down the sides from time to time to keep everything moving evenly, and if the mixture just won't move through the baldes, add a little water to loosen it up. Scrape the purée into the bowl. Stir in the oregano and vinegar, then add enough water to give this salsa a light consistency.
Taste and season highly with salt — remember, it's a condiment, so a heavy dose of salt will go a long way. Taste again and add a little sugar if you think it's necessary to balance any lingering bitterness in the chiles. If you're planning to use your salsa right away, simply put it into a bowl, otherwise refrigerate and use within 5 days.