A recipe calls for dry chili peppers for my Moroccan fish. I know sweating fresh chili peppers will release the flavor, but how do you release the flavor of dry spices like dried chili peppers?
In some recipes (eg chinese kung bao, some thai and south indian soups), you score the peppers or cut them into coarse pieces, so cooking oil or a broth with some fat or alcohol content can enter and exit the inside while the peppers are sauteed/stir fired with the rest of the food. This tends to dissolve a lot of heat into the liquids without too strong a pepper aroma.
In others (a lot of thai and goan recipes), the peppers are mashed, sometimes with other spices and aromatics, in a mortar and pestle.
In both cases, you have to decide whether to soak the peppers in very warm but not boiling water beforehand. Also, you can shake the seeds out or leave them in. Look at specific recipes for guidance there.
Oh, and a warning: sauteing dried chili can liberate a surprising amount of capsaicin into the air - if you are dealing with, say, a dozen dried thai chili, it can happen that you find yourself coughing violently in a corner. Ventilate well, and if you feel like you are getting overwhelmed, make sure the kitchen is safe and grab some fresh air ASAP.
Oh... and if you are going the first route, it is inadvisable to put any other ingredient in the dish that has the same color as the dried chili. They won't be THAT hot anymore when cooked out, but still not exactly mild, AND many varieties are texturally and flavour-wise unpleasant if accidentally eaten whole.