Melt butter and olive oil in a large skillet over medium heat. Add beans and peas and saute until crisp-tender. Season to taste with salt and pepper. Keep warm.
To prepare the sauce, melt butter and olive oil in another skillet over medium heat. Add shallots and saute until soft. Add mustards and stir to blend. Stir in half-and half, reduce heat to low and cook until warmed. Serve the sauce over the beans and peas.
Serves 8