In a large saute pan, heat 3 tablespoons of the oil over medium-high heat. Add the haricot verts and season with salt and pepper. When they begin to brown, about 5 minutes, remove from the pan and add the remaining 3 tablespoons oil with the mushrooms. Brown the mushrooms, about 8 minutes, and then add the shallots, garlic, rosemary and chili flakes and cook until softened, about 3 minutes. Season with salt and pepper.
Return the beans to the pan and add the sherry vinegar. Stir in the mint and cook until just fragrant. Season as needed.