Steak kebabs in a mustard-bourbon marinade

Ingredients:

• 0.8 kg of marbled tri-tip steak from the loin, cut into pieces of 2.5-4 cm.
• 2 tbsp vegetable oil + extra for grilling
• 3-4 sprigs of thyme
• 3 cloves garlic, crushed
• 2/3 cup bourbon or rye whiskey
• 1 tbsp. l. brown sugar
• 1/4 cup grainy mustard
• 1 small red onion, cut into 2cm pieces.

Preparation:

1. Prepare the marinadeIn a small saucepan, heat the vegetable oil over medium heat. Add the thyme, garlic, and 1/2 teaspoon black pepper and cook, stirring occasionally, until the garlic softens, about 4 minutes. Remove from the heat, carefully pour in the bourbon, and return to the heat. Simmer until the liquid has reduced by more than half, about 5 minutes. Pour into a large bowl; stir in the brown sugar, mustard, and 1/2 teaspoon salt. Let cool to room temperature.
2. Place the meat in a bowl, mix well and leave to marinate in the refrigerator for 2-6 hours.
3. Soak twelve 8-10 inch (20-25 cm) wooden skewers in water for about 30 minutes to prevent them from burning on the grill. Preheat the grill to medium-high heat. Remove the meat from the marinade, discarding the garlic and thyme. Thread the steak and red onion onto the skewers. Season the kebabs with salt and black pepper.
4. Brush the grill grate with vegetable oil. Grill the kebabs, turning occasionally, until the onions and steak are well browned, 4 to 7 minutes for medium-rare.