In a small bowl, mix ketchup, mustard, curry powder, paprika, and chilli/cayenne pepper.
Finely dice or grate the onion. Mix half of the onion into the sauce and season with salt and pepper.
Authentic Bosna is made with a white, long roll that is sliced lengthwise, toasted on a grill or pan, and slightly stretched to fit the sausages. Two Bratwurst sausages are the standard, which makes Bosna more substantial than a typical hot dog.
The spicy curry onion mixture is key. Some use a mix of ketchup, mustard, and curry, while others use fresh, lightly fried onions. In this recipe, we will use a combination of a fresh and warm mixture.
In a small bowl, mix ketchup, mustard, curry powder, paprika, and chilli/cayenne pepper.
Finely dice or grate the onion. Mix half of the onion into the sauce and season with salt and pepper.
Heat a little oil/butter in a pan (or on a grill) and fry the Bratwurst sausages on all sides until evenly browned and cooked through.
Slice the rolls lengthwise (but not completely through) and lightly toast the inside of the roll on the pan to make it crispy and slightly open.
Fry the remaining half of the sliced onion in a pan until golden and add an extra pinch of curry powder to it. This step adds extra depth to the Bosna.
Place two hot Bratwurst sausages into the toasted and opened roll (place them closely side by side).
Drizzle the sausages evenly with the curry sauce/mixture.
Top with the warm, fried curry onion (from Step 3).
Serve immediately while the roll is crispy and the sausage is hot.