Bring a large pot of salted water to a boil. Add the green beans and carrots and cook until crisp-tender, about 5 minutes. Drain and pat dry with paper towels.
In a large skillet, toast the pine nuts over moderate heat, stirring constantly, until lightly golden, about 5 minutes. Transfer the pine nuts to a plate to cool.
Heat the oil in the skillet until shimmering. Add the mushrooms and cook over moderately high heat, stirring, until softened and beginning to brown, about 5 minutes. Add the carrots and green beans and cook, stirring, until tender, 3 to 4 minutes. Add the tomatoes and lemon juice and season with salt and pepper. Cook until the tomatoes are just warmed through, about 1 minute. Transfer the vegetables to a platter, sprinkle with the pine nuts and serve.
The recipe can be prepared through Step 2 and refrigerated separately for up to 2 days.
One Serving Calories 104 kcal, Total Fat 7.1 gm, Saturated Fat 0.8 gm.