Preheat the oven to 200°C. Peel and cut the potatoes in 8 pieces each. Use a large baking dish (my dish’s measurements L330mm x W270mm x H65mm) to add the potatoes and onions in. Mix in the seasonings, olive oil and lemon juice until all is well distributed. Then add enough water to cover about 1/3 of the potatoes’ height (for my tray I required 300mL).
Cover the baking dish with aluminum foil and place it in the oven for the first 20min and then uncovered for the next 25min or until the potatoes get a bit of colour.
While the potatoes are cooking prepare the mince mixture, to allow enough time for the flavours to combine (see notes). Use a food processor to blend all the ingredients together, except the mince and breadcrumbs. If you do not have a food processor, just chop the onion and parsley finely and mince the garlic cloves.
Pour the processed mixture into a bowl with the mince and breadcrumbs. Use your hands to combine everything until the marinade is evenly spread.
While the potatoes are cooking form the patties. Get a baking tray, line it with baking paper. Form 8 equal patties (mine were about 160g each), place them on the lined tray in a single layer and put the tray in the fridge covered. If the potatoes are nearly ready to come out of the oven (after 45min) then you may just leave the beef patties covered on the kitchen bench.
Once the time for the potatoes is over, take out the baking dish and add the tomato slices and the ready-made patties on top of the cooked potatoes. There will probably be no liquid left in the tray but that's ok. Do not add any, the beef patties will release a lot of juices.
Place the baking dish back in the oven uncovered, for a further 17-20min or until the patties are just browned. Enjoy the meal warm with some salad and yoghurt on the side!
For this recipe I use red onion instead of brown as it is sweeter and digested easier. The patties will only be cooking for a short period of time hence using red onion will not be as much of an issue. If you do use brown onion I recommend you sauté it first on its own, let it cool down and then add it in the beef mixture.
The preparation can all be done from the day before, including the mince mixture but also peeling and cutting the potatoes. I just usually place the chopped potatoes in a big bowl covered with water. If it is very hot during the day I place it in the fridge, otherwise I leave the bowl with potatoes on the kitchen bench.
The total time needed for the recipe is reduced from what is stated above because you prepare the mince mixture and patties while the potatoes are cooking.