Cut each piece of frozen roti into four quarters.
Divide the minced beef into eight portions. Press each portion thinly and evenly onto a roti quarter, making sure the meat extends right to the edges.
Season the beef lightly with salt and freshly ground black pepper.
Heat a little oil in a non-stick frying pan over medium-high heat.
Place the roti quarters meat-side down in the pan. Cook for approximately 2–3 minutes, until the beef develops a browned crust.
Flip the pieces over and cook for another 2–3 minutes, until the roti is golden and crispy and the beef is fully cooked. Work in batches if necessary.
Meanwhile, blend the yoghurt, feta, pickled cucumbers and ketchup until creamy. Adjust the ingredients to taste.
Serve the smash burger roti immediately with the sauce for dipping or drizzling.