Garlicky Butter Steak Bites

Bahan-bahan (6 porsi)

• 1 ½ lbs skirt steak
• 1 teaspoon kosher salt
• ½ teaspoon freshly ground black pepper
• 4 tablespoons butter (divided)
• 6 cloves garlic (minced)
• optional: thinly sliced green onions