Untested recipe.

Substitutions:

• Beef braising steak — at Aldi, use British Diced Beef (5% fat) or Brisket Joint (cut into chunks). The Brisket Joint is the better option here — it’s naturally fatty and collagen-rich and will produce a richer, more unctuous curry sauce. The Diced Beef at 5% fat is lean (likely topside or silverside diced rather than chuck), so cook in plenty of liquid and don’t overrun the time. Add a little extra coconut milk at the end if the sauce looks thin or the meat seems dry. Avoid the Roasting Joint — likely topside, which goes grainy with long cooking.
• Panang curry paste — available at most Asian shops, sometimes in larger supermarkets. Red curry paste can substitute; Panang is thicker and nuttier, so add a tablespoon of peanut butter to red paste to approximate it.
• Kaffir lime leaves — sold fresh or frozen at Asian shops; a small bag goes a long way and they freeze well. If genuinely unavailable, a strip of lime zest adds some of the citrus note, though it’s not the same.
• Palm sugar — brown sugar or regular sugar is a fine substitute. Coconut sugar from most supermarkets is also good here.
• Fish sauce — soy sauce can substitute at a push, but fish sauce is worth keeping stocked for Thai cooking generally.