In a large bowl, combine the vegetable oil, soy sauce, lemon juice, minced garlic, ground cumin, ground coriander, paprika, turmeric, cayenne pepper (if using), salt, and black pepper.
Add the beef or chicken pieces to the marinade and toss to coat well.
Cover the bowl and refrigerate for at least 1 hour, or overnight for best results.
Preheat your grill or grill pan to medium-high heat.
Thread the marinated meat onto the skewers.
Place the skewers on the grill and cook for about 10-15 minutes, turning occasionally, until the meat is cooked through and has a nice char.
The cooking time may vary depending on the size of the meat pieces and the heat of the grill.
Enjoy your meal!