Method

1. For the falafel: Preheat the oven to 220C and roast the sweet potatoes whole until just tender (about 45 minutes - 1 hour).

2. Turn off the oven, leave the potatoes to cool, then peel.

3. Put the sweet potatoes, cumin, garlic, ground and fresh coriander, lemon juice and gram flour into a large bowl.

4. Season well and mash with your hands or a potato masher until you have a smooth mix with no large chunks.

5. Stick in the fridge to firm up for an hour, or the freezer for 20-30 minutes.

6. When you take it out your mix should be sticky rather than really wet and you can add a tablespoon or so more gram flour if necessary (sweet potatoes vary in water content enormously).

7. Heat the oven to 200C.

8. Using a couple of soup spoons (put a well-heaped spoonful of mix in one spoon and use the concave side of the other to shape the sides), or a falafel scoop if you have one, make the mixture into small patties and put them on an oiled baking tray.

9. Sprinkle sesame seeds on top and bake in the oven for approximately 15 minutes, until the bases are golden brown.

10. For the aïoli: Using an electric mixer on a medium speed, combine the egg and egg yolk with the garlic for a few minutes until pale and fluffy.

11. Start drizzling in the oil slowly, as if making mayonnaise or hollandaise sauce until all the oil is incorporated.

12. Stir or fold the yoghurt in gently by hand and finish with the lemon and salt.

13. Serve cupped in or with flatbreads with salad and pickles.