Grind or mash douchi with garlic and a bit of light (OK, usually light) soy sauce. You could add vinegar, (Chinese) wine, stock, or whatnot to dilute and thin, if you like. Douchi, FWIW, is fermented black beans with salt. And, come to think of it, even though you almost always see it, the garlic is optional.
And, come to think a little more of it, you can buy bean paste or bean sauce already made, but it's a lot better and no trouble to make your own from douchi. Now douchi is something you do buy ready-made. Note: Lee Kum Kee brand douchi may not be the absolute best, but it's widely available and just fine.
1st Question: How would you make the al diablo sauce for pescado or camarones al diablo? In other words, a good recipe.
2d (and related) Question: How hot (picante) do you like yours?
Note: It's one of my favorite dishes, and I'm serious about improving my own recipes and presentations. You don't have to be too mainstream. Please share any thoughts you have on twists, takes or plays. Lately, I've been puddling the sauce as a sort of mole and presenting grilled fish or shrimp on top of it. But the best I ever had (Jacalito on Valley Blvd., in El Monte) is served more prosaically with the fish (or shrimp) swamped in the sauce. I like mine very, even ridiculously hot; and Jacalito makes it that way -- you pretty much need to sign a waiver before they'll serve it. However, I don't cook it that way so as not to blow other people out.