For the BBQ sauce:
1) Heat the oil over a medium-high heat in a heavy-bottomed medium saucepan. Add the onions and cook until soft, 3 to 4 minutes. Add the garlic and cook for 1 minute. Add the ketchup and water, bring to a boil and simmer for 5 minutes. Add the remaining ingredients and simmer for an additional 10 minutes until thickened, stirring occasionally.
2) Transfer the mixture to a food processor and puree until smooth. Season with salt and pepper to taste, pour into a bowl and allow to cool at room temperature. The sauce will keep for 1 week in the refrigerator stored in a tightly sealed container.
For the barbequed onions:
1) Heat the griddle to medium. Brush the onion slices with oil and season with salt and pepper. Season one side of the slices with the BBQ rub.
2) Cook the onions rub-side down until lightly golden brown. Flip over, brush with BBQ sauce and cook until just cooked through. Separate the slices into rings and serve.
For the pickled peppers:
1) Combine the vinegars, garlic, sugar and salt in a small saucepan over a high heat and bring to the boil. Boil until the sugar is dissolved then remove from the heat and allow to cool to room temperature.
2) Put the peppers and oregano in a medium bowl, add the vinegar mixture and stir to combine. Cover and refrigerate for at least 4 hours and up to 2 days.
For the avocado crema:
1) Combine the avocados, water, lime juice, rice vinegar and honey in a blender and blend until smooth. Add the coriander, salt and pepper and blend a few seconds just to incorporate.
For the fajitas:
1) Combine the curry paste, oil, and 60ml of the lime juice in a food processor and process until smooth.
2) Place the steak in a large baking dish and add half the marinade. Turn to coat the steak in the marinade, cover and refrigerate for at least 4 hours and up to 8 hours.
3) Whisk together the honey and the remaining 2 tablespoons of lime juice in a bowl to make a honey-lime glaze. Heat the griddle to high or place a cast iron pan over a high heat.
4) Remove the steak from the marinade and season with salt and pepper on both sides. Cook the steak until golden brown and slightly charred on both sides, brushing with honey-lime glaze a few times; for medium-rare, about 12 minutes total.
5) Remove from the griddle and leave to sit for 10 minutes before slicing across the grain into thin slices. Place the meat on a platter and immediately drizzle with the honey-lime glaze.
6) Lay warm tortillas on a flat surface, put a few slices of the beef down the centre, top with onion slices, pickled peppers and a dollop of avocado crema. Roll and eat immediately.