In a mixing bowl, combine the steak cubes with soy sauce, olive oil, salt, and black pepper. Let marinate for at least 30 minutes.
Melt the butter in a small pan over low heat. Stir in minced garlic and cook for 1 minute until fragrant. Remove from heat.
Thread the marinated steak onto skewers, leaving a little space between each piece for even cooking.
Preheat the grill or grill pan to medium-high heat. Lightly oil the grates to prevent sticking.
Grill the skewers for about 3-4 minutes per side, or until desired doneness is reached. In the last minute of cooking, brush the steak with garlic butter.
Remove from the grill and let the skewers rest for 5 minutes before serving. Garnish with fresh parsley.