Preparation Heat oil and butter in a large heavy skillet over medium-high heat until foam subsides, then cook zucchini, undisturbed, until undersides are golden brown, about 8 minutes. Turn over and cook until undersides are golden brown, about 6 minutes. Add vinegar and 3/4 teaspoon salt and cook, shaking skillet, until vinegar has evaporated. Remove from heat; crumble in mint. Add 1/4 teaspoon pepper and toss.
Preparation Heat oil and butter in a large heavy skillet over medium-high heat until foam subsides, then cook zucchini, undisturbed, until undersides are golden brown, about 8 minutes. Turn over and cook until undersides are golden brown, about 6 minutes. Add vinegar and 3/4 teaspoon salt and cook, shaking skillet, until vinegar has evaporated. Remove from heat; crumble in mint. Add 1/4 teaspoon pepper and toss.