1. Start by soaking your wooden skewers in water for at least 30 minutes to prevent them from burning on the grill.
2. In a large bowl, combine olive oil, minced garlic, chopped rosemary, balsamic vinegar, salt, and pepper. Stir well to create a marinade.
3. Add the cubed beef to the bowl, ensuring that each piece is well coated with the marinade. Cover and refrigerate for at least 1 hour, or overnight for deeper flavor.
4. Preheat your grill to medium-high heat. If you’re using an indoor grill pan, heat it over medium-high heat as well.
5. Assemble the kebabs by threading the marinated beef, red bell pepper, yellow bell pepper, and red onion onto the skewers, alternating between each ingredient.
6. Place the skewers on the grill and cook for about 8-10 minutes, turning occasionally, until the beef is cooked to your desired level of doneness and the vegetables are tender.
7. Remove the kebabs from the grill and let them rest for a few minutes before serving. This allows the juices to redistribute, ensuring every bite is juicy and flavorful.

These steps embody the simplicity and joy of cooking that I’ve learned from years of watching my abuela create magic in the kitchen. Trust your senses, and don’t be afraid to adjust the seasonings to your liking!