In a medium mixing bowl, whisk the eggs together with the salt and black pepper until well combined. Set aside.

Heat 1 tablespoon of oil or butter in a large skillet or flat griddle over medium-high heat. Add the diced onion and minced garlic, sautéing until fragrant and softened, about 2 to 3 minutes.

Add the ground beef and curry powder to the skillet. Cook, breaking the meat apart with a spatula, until browned and cooked through, about 5 to 7 minutes. Stir in the sambal oelek if using.

Spread the cooked beef mixture out slightly in the pan to match the length and width of your opened baguette. Pour the whisked eggs evenly over the beef.

Immediately open the sliced baguette and press it cut-side down directly onto the wet egg and beef mixture. Press down firmly so the soft bread absorbs the egg and binds to the meat.

Cook for 2 to 3 minutes until the egg is completely set and firmly attached to the bread. Carefully slide a large spatula under the egg layer and flip the entire sandwich over to toast the outside of the bread for 1 to 2 minutes until crispy.

Remove the Roti john from the skillet and transfer to a cutting board. Drizzle the meat side with sweet chili sauce and mayonnaise, fold the sandwich closed, and cut into 3-inch portions to serve hot.