01 - Rinse rice under cold water until clear. Bring 2 cups water to a boil. Add rice, salt, and butter. Reduce heat to low, cover, and simmer 12–15 minutes until tender. Fluff with a fork and keep warm.
02 - Toss beef strips with flour, salt, and black pepper evenly.
03 - Heat 1 tbsp olive oil and 1 tbsp butter in a large skillet over medium-high heat. Sear half the beef until browned but still pink inside, about 1–2 minutes per side. Remove to a plate.
04 - Repeat searing with remaining beef, adding more oil if needed. Remove from skillet.
05 - Add remaining butter to skillet. Sauté onions for 4 minutes until translucent. Add garlic and mushrooms; cook 5–6 minutes until mushrooms brown and liquids evaporate.
06 - Stir in tomato paste, Dijon mustard, and paprika; cook for 1 minute to blend flavors.
07 - Pour in beef broth, scraping browned bits from pan. Simmer for 3 minutes to slightly reduce.
08 - Lower heat. Stir in sour cream gently without boiling. Return beef and juices to pan; simmer 2–3 minutes until beef is cooked and sauce is creamy. Adjust seasoning with salt and pepper.
09 - Plate beef stroganoff over basmati rice and garnish with chopped parsley.