This African-inspired burger contains suya – a fiery spice mix popular in West Africa. If you don’t enjoy very spicy food, reduce the amount of chilli powder in the recipe.
For the suya spice
- 4g smoked paprika
- 2g cayenne pepper
- 6g ginger powder
- 4g garlic powder
- 1g ground black pepper
- 11g onion salt
- 7g ground turmeric
- 6g extra hot chilli powder
- 1g ground uda pods (also known as selim pepper)
For the ‘suyannaise’
- 1 large egg yolk
- 4 tsp suya spice (see above)
- 2 tsp fresh lemon juice
- 125ml/4fl oz rapeseed oil
- 1-2 tsp just-boiled water
For the watermelon salad
- 75g/2½oz peeled and deseeded watermelon, cut into 1cm/½in cubes
- 75g/2½oz cucumber, cut into 1cm/½in cubes
- 75g/2½oz feta cheese, cut into 1cm/½in cubes
- 1 tbsp finely chopped fresh curly leaf parsley
- large pinch nigella seeds, toasted
For the sweet potato cubes
- 200g/7oz purple sweet potato (see tip)
- 200g/7oz sweet potato
- vegetable oil, for deep frying
For the caramelised onions and burger
- 1 medium red onion, cut into rings
- 2 tbsp olive oil, for frying
- 1 tsp golden caster sugar
- 2 x 125g/4½oz beef fillet steaks
- ½ tsp coarsely ground black pepper
- 2 white ciabatta rolls, cut in half
- 2 tbsp ‘suyannaise’ (see above)
- 1 beef tomato, sliced into rounds
- 1 Little Gem lettuce, shredded
- 2 tsp suya spice, plus extra to taste
- 50g/1¾oz smoked cheddar, grated
To make the suya spice, put all the ingredients in a jam jar, seal and shake.
For the ‘suyannaise’, put the egg yolk into a medium bowl and whisk with the suya spice and lemon juice until pale. Add a little oil, whisk again. Whisk continuously adding the remaining oil gradually in a thin stream until the mayonnaise is very thick.
Once all the oil is combined, add the boiling water and whisk until the mayonnaise has a soft, dropping consistency. (You can also make the mayonnaise in a small food processor.) Transfer to a small bowl, cover the surface with cling film and store in the fridge.
For the watermelon salad, mix the melon, cucumber, feta and parsley in a bowl and top with toasted nigella seeds. Set aside.
For the sweet potato cubes, cut the sweet potato into 2cm/¾in cubes. Half-fill a medium saucepan with water and bring to the boil. Add the sweet potato and cook for 5½ minutes, then drain in a sieve and leave to stand to cool and dry.
For the caramelised onions, save a few of the larger onion rings to serve raw inside the burger. Heat a tablespoon of the oil in a small non-stick saucepan over a low heat and gently fry the remaining onion for 6–8 minutes or until very soft and lightly browned, stirring regularly. Add the sugar and cook for a few seconds more, stirring. Set aside.
Preheat a deep-fat fryer to 180C. (CAUTION: hot oil can be dangerous. Do not leave unattended.)
For the burger, place the steaks on a board and cover with a sheet of cling film. Bash with a rolling pin or the base of a heavy saucepan until around 15mm/⅝in thick, then season with the pepper.
Heat the remaining tablespoon of oil in a medium non-stick frying pan and fry the steaks for 1½ minutes on each side, over a high heat or until cooked to your liking. Set aside to rest for 5 minutes.
Add the sweet potato cubes to the fryer and cook for about 4 minutes or until golden-brown. Drain on kitchen paper.
Meanwhile, lightly toast the bread buns. Divide the bun bases between two plates. Top each one with a tablespoon of suyannaise, lettuce, slices of tomato and the reserved sliced red onion.
Sprinkle the rested steaks in suya spice and crumble the cheese on top. Melt with a blowtorch or place on a baking tray under a preheated hot grill until melted. Place in the bun and top with caramelised onions.
Serve the burgers with the watermelon salad and hot sweet potato cubes on the side.
Suya spice is also available premixed in case you find it difficult to assemble all the different spices needed. The suya spice recipe above makes a little more than you’ll need, but it keeps well in an air-tight container.
If purple sweet potatoes aren’t readily available, it’s fine to use normal sweet potatoes instead.