To make your own curry paste pound all ingredients into a stone pestle and mortar. Add ingredients in the order they are listed to ensure the paste reaches a smooth consistency. Alternatively, shop bought red curry paste can also be used.
Take 1 tablespoon of the curry paste and combine with 2 tablespoons of fish sauce, 1 tablespoon of palm sugar and 3 tablespoons of water to make a thick marinade. Massage this over the Irish rump and leave to marinate for 4 hours.
Cut the celeriac into large chunks and boil in salted water until tender, then cool on a dry rack. Once cool, grill the celeriac chunks over a high heat while basting with the salted coconut cream. Continue to turn and baste so the celeriac develops a dark colour from the charcoal grill. Remove and cut into bite size pieces.
Grill the Irish rump over a medium-high heat to give nice caramelisation and colour. This will take around 5 minutes depending on the heat of your charcoal grill and the thickness of your rump, you want the end result to be a medium cook with a blushing pink interior. To ensure a medium cook, use a temperature probe and check the internal core is 45-50 degrees before removing and resting the meat. You are looking to reach 55 degrees internal temperature after resting for a medium cook.
In a pan combine the coconut oil and coconut cream. Warm over a medium heat until the oil forms a sheen on the surface of the cream, for about 1 minute.
Add the curry paste and cook until fully incorporated with the cream, continue to fry until the paste becomes fragrant and darkens – this indicates the rawness from the curry paste has been cooked out, for about 4 minutes.
Add the palm sugar and fish sauce and allow to cook into the paste. Then add the remaining coconut cream and stock/water. Bring to a boil and then reduce to a simmer and cook for a few minutes until the sauce develops a slight oily sheen on the surface.
Add the charcoal grilled celeriac, sliced chillies and kaffir lime leaves, continue to simmer.
Remove from the heat and allow to sit for a minute so the flavours can develop together. Taste and adjust seasonings using palm sugar and fish sauce as you deem appropriate, it should taste rich, slightly spicy, sweet and salty.
Slice your rested Irish rump steak, look for the grain of the meat and cut in the opposite direction, this will make the steak more tender and delicious. Add the sliced beef and Thai basil to the curry and gently fold together to coat in the rich sauce.
Serve garnished with a splash of coconut cream and finely shredded kaffir lime leaves.