Heat a sauce pot over medium heat, add butter to the pot and melt. Add almonds and toast 3 to 4 minutes. Add rice and the zest of an orange and a lemon then turn the rice to coat, cook 1 minute. Add stock and bring to boil, reduce to simmer, cover and cook 17 to 18 minutes.
While rice cooks, heat a large skillet over medium-high heat with 3 tablespoons olive oil, 3 turns of the pan. Pat meat dry. When oil ripples and begins to smoke, add the beef and brown 3 minutes on each side. Remove when evenly deep brown and reserve on plate.
Add remaining olive oil to skillet, 3 turns, heat until oil ripples then add mushrooms and brown 7 to 8 minutes. Add garlic after 5 to 6 minutes. Season mushrooms with salt and pepper cook a few minutes more. Add sherry, reduce 1 minute, add beef stock and beef tips and their juices to pan. Reduce heat and cook 3 to 4 minutes more. Turn off heat.
Fluff rice with fork and serve with the beef and mushrooms.