Prepare the pasta according to the directions on the package.
Over medium heat, add olive oil to a pot. Once the pot is hot, add the beef. Once browned on both sides, remove the beef and set aside.
Add 1 tablespoon of butter, broccoli, onions, mushrooms, and garlic to the drippings and stir to coat. Cook until the vegetables have softened and the onions become opaque.
Remove the vegetables from the heat and set aside. Add 2 tablespoons of butter to your pot along with the flour and stir to incorporate until you have a paste. Slowly stir in milk and bring to a simmer.
Add thyme, ground mustard, and black pepper and stir to incorporate.
Place your cooked beef and vegetables back into the pot with the mixture, add salt, and stir to incorporate. Bring to a boil, then remove from heat.
Spoon beef stroganoff over cooked pasta. Garnish with shredded cheese and chives to taste.
Serve while hot, and enjoy!
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Notes
Take the time to sauté the onions and garlic until they become translucent and develop a sweet aroma. This step helps build a solid flavor foundation for your stroganoff.
When cooking the beef, brown it nicely on all sides. This helps caramelize the meat and develop a rich flavor for your stroganoff. Avoid overcrowding the pan, as it can lead to steaming instead of browning. Cook the beef in batches if necessary.
To prevent the milk from curdling, gradually add it to the skillet while stirring constantly. This helps ensure a smooth and creamy sauce.