Preheat oven to 425°F. Line a large sheet pan with parchment paper or foil.
Microwave the baby potatoes in their steamable container according to package directions (usually 5 minutes). Let cool slightly, then carefully halve or lightly smash if desired.
In a small bowl, whisk together the melted butter, minced garlic, salt, pepper, and smoked paprika. Set aside.
Toss the steak bites in half of the garlic butter mixture. In a separate bowl, toss the green beans, mushrooms, onions, and microwaved potatoes with the remaining olive oil.
Spread everything evenly on the sheet pan and drizzle the remaining garlic butter over the top.
Roast for 15 minutes, stirring once halfway through, until the steak is cooked to your liking and the vegetables are golden and tender.
Garnish with parsley if desired and serve hot.
Notes
Pls not I like my steak tender and well done, if you don't--I recommend adding the steak later. Increase the temperature to 450 and cook until desired doneness.