Mash garlic, salt, and peppercorns using a mortar and pestle or food processor until a paste forms.

Stir in orange juice (or sour orange juice alternative).

Let the mixture sit at room temperature for at least 30 minutes to allow flavors to meld.

If making a marinade without oil, stop here and use the mixture to season chicken, fish, pork, or beef.

To continue preparing the mojo with oil, add minced onion and oregano to the juice mixture.

Let the mixture sit at room temperature for at least 30 minutes.

Heat olive oil in a saucepan over medium heat until medium hot.

Remove the saucepan from heat.

Gradually whisk the hot oil into the garlic-juice mixture until well blended and emulsified.

Store the mojo in the refrigerator for up to a week.