In a large pot of boiling, salted water, cook the linguine until al dente; drain. Meanwhile, in a large skillet, cook the onion and garlic in 1/4 cup extra-virgin olive oil over medium heat until tender and translucent, about 5 minutes. Add the asparagus and 1/4 cup water; cover and cook until the asparagus is tender but still crisp, about 4 minutes more. season to taste with salt, pepper and crushed red pepper. Add the linguine and toss.