Heat a splash of cooking oil in a skillet over medium heat, then add the chopped red onion and minced garlic, sautéing until fragrant and translucent, about 3 minutes.

Add the ground beef and curry powder to the skillet, breaking up the meat with a wooden spoon, and cook until fully browned and cooked through, about 5 to 7 minutes.

Remove the beef mixture from the heat, drain any excess fat, and let it cool slightly for a few minutes.

In a medium bowl, whisk the eggs with a pinch of salt and pepper, then stir in the cooked beef mixture until well combined.

Melt one tablespoon of butter in a large non-stick skillet over medium-low heat, then pour in half of the egg and beef mixture, spreading it to match the length of your split baguette.

Immediately place one half of the split baguette, cut-side down, directly onto the egg mixture, pressing down gently with a spatula so the bread and egg stick together.

Cook for 3 to 4 minutes until the egg is completely set and golden brown, then carefully flip the sandwich over to toast the crust of the bread for 1 to 2 minutes.

Repeat the process with the remaining butter, egg mixture, and the other half of the baguette.

Transfer the roti john to a cutting board, open it up, and top with shredded cabbage, cucumber slices, and a generous drizzle of mayonnaise and sweet chili sauce before slicing into portions and serving warm.