Finely grate or mince 1 garlic clove and place in a mason jar. Add 1/2 cup extra-virgin olive oil, 1/2 cup red wine vinegar, 2 teaspoons Dijon mustard, 2 teaspoons dried oregano, 1 teaspoon kosher salt, and 1/2 teaspoon black pepper. Seal the jar and shake well to combine and emulsify. (Alternatively, place all the ingredients in a small bowl and whisk well to combine.)