Learn Spanish (Latin America): Para adornar la copa, tienes que medir la onza. - To garnish the glass, you have to measure the ounce.

While adornar literally means "to decorate" or "to adorn," in the culinary context of preparing food and mixed drinks, it is the standard Spanish way to say "to garnish."

Why is copa used for "glass" instead of vaso?

The word copa specifically refers to a stemmed glass, such as a wine, martini, or margarita glass. A vaso is a standard cylindrical drinking glass with no stem. The context of measuring ounces and garnishing points to a cocktail served in a copa.

Why does this sentence use para instead of por?

The preposition para is used to express purpose or a specific goal, translating perfectly to "in order to" in English. Here, the goal is adornar la copa. Using por would incorrectly imply a cause or reason.

Why do we use the infinitive adornar immediately after para?

Because there is no change of subject. The person who has to measure the ounce is the same person who is garnishing the glass. If you wanted someone else to garnish the glass, you would have to use para que followed by a conjugated verb in the subjunctive.