Prepare linguine according to package directions.Meanwhile, place the avocado in a bowl, mash with a fork until smooth, then mix in the lime juice. (This is where you can use your frozen {defrosted} avocado mixture). Then add the greek yogurt and salt. Mix till smooth, set aside.Meanwhile heat the olive oil in a large skillet over medium high heat, cook the onion, garlic and steak until the steak is cooked to your liking. Strain the steak mixture.Drain the pasta and toss in the avocado sauce. Divide the pasta between 4 bowls and top with the steak mixture, the roma tomatoes, and a little cilantro.Enjoy!