Pat the steak cubes dry with paper towels and season them evenly with salt and pepper.
Heat the olive oil in a large skillet over medium-high heat until shimmering.
Add half of the steak cubes to the hot skillet, ensuring not to overcrowd the pan. Sear for 2-3 minutes per side until browned. Remove the first batch and set aside. Repeat with the remaining steak.
Reduce the heat to medium. Add the sliced mushrooms to the same skillet and cook, stirring occasionally, until they release their moisture and start to brown, about 5-7 minutes.
Push the mushrooms to one side of the skillet. Add the butter to the empty space. Let it melt until it begins to foam.
Add the minced garlic and thyme to the melted butter. Cook for about 30 seconds until fragrant, stirring the garlic into the butter and mushrooms.
Return all the seared steak bites to the skillet. Toss everything together quickly to coat the steak and mushrooms in the garlic butter sauce. Cook for 1 minute to heat through. Do not overcook if you prefer medium-rare.
Remove the skillet from the heat immediately. Stir in the remaining salt if needed.
Garnish with fresh chopped parsley before serving.
Notes
For medium-rare steak bites, aim for an internal temperature of 130-135°F.
Serve these steak bites over rice, mashed potatoes, or egg noodles for a complete meal.
If you prefer a richer sauce, use brown butter by cooking the butter until the milk solids turn golden brown before adding the garlic.