How to Make It
In a large pot of salted boiling water, blanch the haricots verts for 2 minutes. Drain and transfer the beans to a baking sheet to cool. Using a sharp knife, split the beans lengthwise down the middle.
In a large skillet, melt 1 tablespoon of the butter in 1 tablespoon of the oil. Add the mushrooms and cook over high heat, stirring occasionally, until tender and golden, 5 to 7 minutes. Add the shallots and the remaining 1 tablespoon of olive oil and cook, stirring, until softened, 2 to 3 minutes longer. Stir in the haricots verts, then gradually add the remaining 2 tablespoons of butter, stirring constantly. Stir in the Salted Herbs and serve immediately.