1. Combine all the ingredients marked * in a bowl and mix well. Add diced beef and toss until well coated and then cover with clingfilm. Set aside in the fridge for a minimum 2 hours or preferably overnight.
2. Heat a splash of olive oil in a pot. Once the pot is hot, add onions. Saute till golden brown. Add marinated beef and fry for about 5 minutes, stirring occasionally.
3. Stir in chopped tomatoes and season with salt and pepper. Next, add potatoes, carrots and aubergines. Pour in 1 cup of water before adding in the chickpeas, mixed beans and prunes. Give everything a gentle stir and put the lid on. Continue cooking for another 30-45 minutes or until the meat is tender. Once in a while, check to see if needed to add an extra splash of water.
4. Lastly, once the meat is tender, adjust seasonings and add chopped coriander.
5. Place the beef tagine on a large serving platter. Spoon the vegetables, prunes and gravy on top. Garnish with chopped coriander and serve it hot with your favourite bread, couscous or rice.