I'm not quite sure if sofrito qualifies as a sauce—you most likely won't be dipping anything into this puree of herbs and vegetables—but it's such a powerful base of flavor for stews, rice, and so much more that it deserves its place in the ever-increasing tome of "Sauced."
I first learned of sofrito watching Daisy Cooks on PBS, and have found little reason to veer from the recipe since then. This Puerto Rican version of sofrito—there are many different geographical variations—is a fresh mixture of onions, cubanelle peppers, garlic, cilantro, ajices dulces*, cilantro, culantro*, tomatoes, and red pepper quickly chopped into a fine paste in a food processor. What you're left with is enough sofrito to add some serious flavor to weeks of meals.
* While culantro and ajices dulces are easy to pick up in my neighborhood, Daisy says don't sweat it if you can't find them. The ajices dulces can be omitted, and just substitute another handful of cilantro if you can't find culantro.
My first use was a big pot of yellow rice, with the sofrito imparting a strong herbal flavor with a hint of spice. This was followed by a chicken and potato stew, where a cup of sofrito served as the main flavoring component in a dinner that could easily feed six to eight hungry bellies.
Even after those, I had barely made a dent in my batch of sofrito, so off to the freezer it went, where I can easily tap into it whenever I'm looking to give something a strong fresh flavor. Who knows where the rest will take me, but I'm open to suggestions...