In a large bowl, combine the vegetable oil, groundnut paste, tomato paste, paprika, cayenne pepper, ginger, garlic, black pepper, salt, and soy sauce (if using). Mix well to form a marinade.
Add the beef or goat meat strips to the marinade. Toss to coat all the pieces evenly. Cover the bowl with plastic wrap and refrigerate for at least 1-2 hours, or overnight for more flavor.
If using wooden skewers, soak them in water for about 30 minutes to prevent burning.
Thread the marinated meat strips onto the skewers, leaving a little space between each piece.
Preheat your grill to medium-high heat.
Place the skewers on the grill and cook for 5-7 minutes on each side, or until the meat is cooked through and has a nice charred exterior. Baste occasionally with any remaining marinade.
Remove the skewers from the grill and let them rest for a few minutes.
Enjoy your meal!