Spread the nuts on a baking sheet and toast in the oven until slightly darkened and fragrant, about 8 minutes. Remove the nuts, chop, and set aside.
Top and tail the green beans, and cook them in a large pot of boiling salted water, until tender. Drain and rinse under cold running water to set the colour.
Heat the oil in a skillet, add the shallot, 1 minute, then add the beans and toss to heat through. Season the beans with salt, and pepper. Add a squirt of lemon juice, to taste. Remove the pan from the heat, and stir in the creme fraiche to coat. Toss in the hazelnuts, and chopped herbs. Arrange the beans on a warm platter, and serve.