Begin by grating the large onion using either a hand grater or a food processor. Once grated, place the onion in a fine mesh strainer set over a mixing bowl.

Using your hands or the back of a spoon, press down on the grated onion to extract as much juice as possible. Discard the leftover pulp.

In a separate mixing bowl, combine the extracted onion juice with olive oil, fresh lime juice, salt, ground black pepper, and the saffron infused water. Mix thoroughly until all ingredients are well incorporated, forming a fragrant marinade.

Take the filet mignon and place it on a clean cutting board. Using a sharp knife, cut the meat into equal-sized pieces, approximately 3-4 inches in length. You should have around 6 pieces in total.

Carefully butterfly each piece of filet by making two horizontal cuts, one-third of the way down from the top, and extending about three-quarters of the way across. Repeat this process for all filet pieces.

Using the blunt side of a knife, gently pound each butterflied filet piece to about half its original thickness. This tenderizing process helps to ensure the meat cooks evenly and remains tender.

Transfer the tenderized filet pieces into a shallow pan or dish. Pour the prepared marinade over the meat, ensuring each piece is thoroughly coated. Cover the pan with plastic wrap and refrigerate for a minimum of 2 hours, allowing the flavors to meld.

Preheat your grill, whether it's charcoal or gas, ensuring it reaches the desired temperature for grilling.

Remove the marinated filet pieces from the refrigerator and carefully thread them onto flat and long skewers. Ensure each piece is securely placed on the skewer to prevent them from falling off during grilling.

Once the grill is hot and ready, place the skewered filet pieces over the heat. Grill the kebabs for approximately 6-8 minutes, rotating them frequently to ensure even cooking.

As the kebabs cook, you'll notice them firming up and taking on a beautiful charred appearance.

Once the kebabs are cooked to your desired level of doneness, carefully remove them from the grill.

Serve the Kabab Barg hot, accompanied by your choice of grilled vegetables, flatbread, or a bed of steamed basmati rice for a complete and satisfying meal.