In a large pot of boiling, salted water, cook the orzo until al dente. Drain and return to the pot. Stir in the pine nuts, parsley, lemon juice, lemon peel and 2 tablespoons extra-virgin olive oil. Season with salt and pepper.
In a skillet, heat 1/4 cup olive oil oven high heat until rippling. Add the mushrooms and cook, stirring occasionally, until browned, about 7 minutes. Divide the orzo among 4 plates and top with the mushrooms.