In a medium saucepan, heat the olive oil and butter over medium heat. Once melted, add minced onions and sauté for 3-4 minutes until translucent.
Add sliced mushrooms and cook for an additional 5-6 minutes until tender and golden.
Stir in the rice, dried onion flakes, onion powder, garlic powder, celery seed, pepper, dried parsley, and kosher salt. Cook for another 2 minutes.
Pour in the broth, stir, and bring to a boil. Reduce heat to low and cover with a lid.
Let simmer for 18-20 minutes, or until liquid is absorbed and rice is tender. Avoid lifting the lid frequently.
Remove from heat and let sit covered for 5 minutes. Fluff the rice with a fork and serve warm, garnished with parsley or chives.
