Stir-fry with beef, potatoes and mushrooms

Ingredients:

• 220 g thin slices of beef tenderloin
• 1.5 tsp cornstarch
• 110 g small red potatoes, cut into half-moon slices 0.3 cm thick.
• 1 cup lightly salted beef broth
• 1 teaspoon lightly salted soy sauce
• 3 tbsp + 1 tsp vegetable oil
• 110 g of mushrooms, thinly sliced
• 2 medium carrots, sliced ​​into 0.3 cm thick circles.
• 2 celery stalks, sliced ​​0.3 cm thick.
• 1 clove garlic, minced
• 2 tbsp tomato paste
• 2 tablespoons unsalted butter
• 2 tbsp chopped fresh parsley
• 2 green onions, thinly sliced, plus extra for sprinkling
• Wide egg noodles in butter or mashed potatoes, for serving

Preparation:

1. In a medium bowl, combine the beef with 1/2 teaspoon cornstarch, 1/2 teaspoon salt, and 1/8 teaspoon black pepper. Let sit at room temperature for 15 minutes.
2. Place the potatoes and 1 teaspoon of salt in a large skillet and cover with 2 cups of water. Bring to a boil and cook until tender, about 4 minutes. Drain the potatoes and set aside. Rinse the skillet and wipe dry.
3. In a small bowl, whisk together the broth, soy sauce, 1/4 teaspoon salt, and the remaining 1 teaspoon cornstarch until dissolved. Set aside.
4. Heat 1 tablespoon vegetable oil in the same skillet over medium-high heat. Add the mushrooms in a single layer, season with salt and pepper, and cook, undisturbed, until browned on the bottom, 2 to 3 minutes; transfer to a large bowl. Add 1 tablespoon plus 1 teaspoon vegetable oil to the skillet, then add the beef, spreading it out in a single layer. Cook, undisturbed, until browned on one side but not cooked through, about 1 minute. Transfer to the bowl with the mushrooms.
5. Add the remaining 1 tablespoon of vegetable oil to the pan, then add the carrots and celery. Season with salt and pepper. Cook, stirring, for 1 minute, then add the garlic and cook for 30 seconds. Add the tomato paste and cook, stirring constantly, until slightly darker in color, about 30 seconds.
6. Pour in the beef broth mixture, making sure all the cornstarch is incorporated. Return the beef, mushrooms, and potatoes to the pan. Cook over low heat until the sauce thickens and the flavors are combined, about 2 minutes. Season with salt to taste, if needed. Remove from heat and stir in the butter, parsley, and green onions.
7. Serve with buttered egg noodles or mashed potatoes, garnished with chopped green onions.