Boil a large pot of salted water, add half the box of pasta + cook 4-6 min or until al dente, then drain + return to pot

Meanwhile, heat lightly oiled skillet over med-high, pat beef dry, add to pan in one layer + sear 2 min (for well done add 1 min); flip + cook 1 more min, season with salt/pep; set aside reserving pan juices

Wipe mushrooms clean + thinly slice; heat 1 tbsp oil in same skillet over high, add mushrooms + cook undisturbed 3 min; sauté 3-4 min until browned + tender, season with salt/pep; add beef + ½ cup sauce + warm 2 min until hot

Toss sauce with pasta, divide to plates + garnish with chopped parsley