In a large skillet, melt 2 Tbsp. unsalted butter over medium-high heat. Add 1/2 cup chopped mild onion and cook, stirring, for about 3 minutes, until onion begins to soften. Add 2 pints red cherry or grape tomatoes, and salt and pepper to taste and cook, stirring frequently, 3 to 5 minutes, until tomatoes begin to soften. Stir in 2 Tbsp. finely chopped fresh parsley and transfer to a serving dish. Serve hot. Serves 8.