We do indeed know of a mussels recipe that makes good use of the anise-flavored Pernod liqueur. It also includes tomatoes, but whether it is the recipe you recall from the unnamed restaurant is uncertain.

We actually know of another Pernod-mussels recipe (also including tomatoes), but it involves a fairly involved process of making shrimp stock, and we just don't know how committed you are to finding the right Mussels Pernod. If the linked recipe doesn't fit the bill let us know, and we'll bring out the shrimp-stock-based big guns.