Preheat the oven to 180°C. Roast the tomatoes with a big pinch of salt and 2 tbsp of olive oil, skin side down for 15 – 25 mins until very soft and starting to caramelize a little.
Remove from the oven and cool. Remove the roasted tomatoes from the roasting tray, leaving any liquid behind in the tray. Keep any liquid to add to the yoghurt.
Using a food processor, blend the roasted tomatoes with the garlic until smooth. Put aside 100g of this mix in a bowl, leaving the remaining mix behind in the food processor.
Add the chickpeas to the food processor with the blended tomatoes. Add the shallots, sundried tomatoes or puree, spices and salt and blend until you have a coarse paste. Chill the mixture in the fridge for at least 30 minutes.
Heat 5cm of oil in a saucepan over a moderate – high heat and fry off a teaspoon of the mix to check the seasoning. Adjust with more salt and pepper, if necessary.
Preheat the oven to 160°C.
Mix the reserved, blended, roasted tomatoes and any tomato roasting juices with the yoghurt and season well with a big pinch of salt. Put to one side in a serving bowl.
With the mix ready to fry, ensure you have the oil at a temperature of 180°C. A digital thermometer is best for this, alternatively drop a thin slice of ginger or a cube of bread into the oil, and if it floats and sizzles to the top of the oil turning golden and crisp within 60 seconds, the oil is at a good temperature to deep fry.
The mixture is quite wet and the oil is very hot so do be careful from here. Use two spoons- one to shape and one to scrape the mixture off. Drop spoonfuls of the batter into the hot oil. It should bubble and fry, quickly turning crisp and golden brown, about 2 minutes.
Flip the falafel over to fry on the other side for 1 ½ – 2 minutes more. Work in small batches, 3 or 4 at a time, removing the falafel with a slotted spoon when crisp and golden brown.
Work in batches keeping the cooked fried falafel warm in the oven until you have used up all the mix.
Warm the flatbreads in the oven. Assemble the chopped salad.
To serve, pile some chopped salad onto the flatbread, add some falafel, then the tomato seasoned yogurt, a slick of tahini, hot sauce, if using, and some pickles.