How to Make It
Preheat the oven to 350°. In a large pot of boiling salted water, cook the beans until tender, about 4 minutes. Drain very well on paper towels.
In a large nonstick skillet, heat 1 tablespoon of the oil until shimmering. Add the mushrooms and cook over moderate heat, turning once, until browned, about 6 minutes. Transfer to a plate.
In the same skillet, heat the remaining 1 tablespoon of oil. Add the shallots and cook over moderate heat until lightly browned, about 4 minutes. Add the garlic and cook until fragrant, about 1 minute. Whisk in the coconut milk, red curry paste and the cornstarch mixture until smooth. Add the sauce to the skillet and cook over moderate heat, stirring occasionally, until slightly thickened, about 5 minutes. Season with salt and pepper.
In a large bowl, toss the green beans with the mushrooms. Add the sauce and toss to coat thoroughly. Transfer the beans to a shallow 3 quart ceramic baking dish and sprinkle the peanuts over the top. Bake for about 15 minutes, until heated through and the peanuts are lightly golden.