Chop the Vegetables: Add the baby portabella mushrooms and yellow onion to a food processor. Pulse until finely chopped but not pureed.
Season the Steaks: Pat the steaks dry and season both sides with the kosher salt.
Sear the Steaks: Heat the olive oil in a large skillet over medium-high heat for about 1 minute. Add the steaks and cook for 3 to 4 minutes per side for medium-rare, or longer if desired. Transfer the steaks to a plate and let them rest.
Cook the Bacon: Add the chopped bacon to the same skillet. Cook over medium heat for 4 to 5 minutes, stirring often, until browned and crisp.
Cook the Mushroom Mixture: Stir the chopped mushroom and onion mixture into the skillet with the bacon. Cook over medium heat for 4 to 5 minutes, stirring often, until softened.
Add the Seasoning: Stir in the red pepper flakes and cook for about 30 seconds, just until fragrant.
Deglaze the Pan: Pour in the chicken broth and stir well, scraping up any browned bits from the bottom of the skillet. Cook for 1 minute.
Simmer the Sauce: Add the tomato basil pasta sauce and stir to combine. Reduce the heat to medium-low and simmer for 3 to 5 minutes, until the sauce thickens slightly.
Finish the Sauce: Stir in the chopped Italian parsley and keep the sauce warm over low heat.
Build the Salad: Place the arugula in a large bowl. Add the sliced pears, blue cheese, and walnuts.
Dress the Salad: Drizzle the apple vinaigrette over the salad and toss gently to coat.
Slice the Steak: Slice the rested steaks against the grain into even pieces.
Plate and Serve: Arrange the sliced steak on serving plates and spoon the spicy mushroom marinara over the top. Add the pear arugula salad on the side and finish with the shaved Parmesan cheese.