1. First, make the cheese sauce. Melt the butter in a saucepan over a medium heat. Add the flour and fajita seasoning and stir to combine. Gradually add the milk, whisking until smooth and thickened. Remove from the heat and stir through the chilli cheese mix. Tightly cover with a sheet of baking paper so that it is touching the sauce (to prevent a skin from forming) and set aside to cool slightly.
2. Mix the coleslaw kit, mayonnaise, 5 finely chopped jalapeños, the coriander and lime juice together until evenly combined. Set aside.
3. Heat a griddle pan or barbecue until hot. Brush both sides of the burgers with the oil and cook for 6-8 mins each side until cooked through. Transfer to a plate, cover with foil and leave to rest for 5 mins. Lightly toast the burger buns on the griddle or barbecue.
4. Smooth ketchup onto the base of the burger buns and top with the coleslaw, a slice of tomato and the burger. Spoon over the cheese sauce and top with the remaining jalapeños and lid. Serve with any remaining coleslaw on the side.
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