Licor 43 is said to be a thousand year old recipe handed down from generation to generation. The name is meant to represent the forty-three separate herbs and spices used in its production. It is Spain's biggest liqueur export. Recently, they've begun to recommend serving a shot called a Licor 43 Mini Beer: tiny beer mug with chilled Licor 43 with a float of heavy cream... which ends up resembling the foam head on a beer.
In our own tasting, we find the flavor and taste profile is an herbal sweetness that is in the same class as Benedictine and, like sweet vermouth, is often used as a flavor additive to naturally dry cocktails with brown spirits such as the Manhattan (with bourbon or rye) and even some drinks with aged rums and tequilas. Robert Hess of The Spirit World agrees with us saying, "Consider some of the classic drinks which include a sweet liqueur of some sort as an ingredient: Sidecar, Margarita, Aviation, as well as those that simply use sugar (or simple syrup) as a sweetening ingredient: Daiquiri, Pisco Sour, Old Fashioned, etc. Licor 43 has enough sweetness, along with a slightly complex flavor, in order to possibly be a substitute for the liqueur or sugar in all of those drinks. Try using Licor 43 in some of these drinks and see what you think."
In contrast, About.com in its section on Spanish food suggests use in colas and other carbonated beverages.