Slice the beef into thin strips and cut the peppers and onions into long slices. Mix all the seasoning ingredients together.
Heat the plancha plate until very hot and add 1 tbsp oil. Cook the onions first for about 2 minutes, then add the peppers. Stir occasionally until they are nicely cooked but still have some bite. Push the vegetables to one side of the plancha.
Add the second tablespoon of oil and spread the beef in a single layer on the plancha. Cook for 1 minute, then stir. Sprinkle the seasoning mix over the beef and mix well.
Combine the vegetables with the beef and cook for another 1–2 minutes until everything is hot and nicely colored.
Warm the tortillas briefly on the plancha and serve with the fajita mix, a generous spoon of sour cream, a squeeze of fresh lime juice, and sprinkle on some cheese
A cold drink on the side and even the busiest workday will feel like a holiday.