Place peeled and cubed potatoes in a large pot, covering them with cold water. Add a pinch of salt and bring to a boil over medium-high heat. Reduce heat and simmer for about 15 minutes or until potatoes are fork-tender.

Drain the potatoes and return them to the pot. Add milk and butter, then mash until smooth and creamy. Season with salt and pepper to taste.

Heat vegetable oil in a large skillet over medium-high heat. Add steak bites in batches to avoid overcrowding. Cook for 2-3 minutes per side for medium-rare or until desired doneness. Remove and set aside.

In the same skillet, reduce heat to medium. Add minced garlic and cook for 1 minute until fragrant. Stir in butter, thyme, and rosemary, letting the butter melt and become aromatic.

Return the steak bites to the skillet, tossing them in the garlic butter sauce. Let them heat through for an additional minute, then season with salt and pepper to taste.

Plate the mashed potatoes and top them with the garlic butter steak bites. Drizzle any remaining garlic butter over the top for extra flavor.