Pierce the sweet potato several times with a sharp knife or fork. Cook it in the microwave for about 10 minutes or until soft. Alternatively, roast it in the oven at 400°F (200°C) for around 45 minutes.

While the sweet potato is cooking, mash the chickpeas in a bowl and add onion, garlic, cayenne pepper, cumin, coriander, paprika, baking powder, salt, flour, and lemon juice.

Once the sweet potato is ready, mash it into the chickpea mixture. Cover and chill in the fridge for at least 30 minutes.

After chilling, form spoonfuls of the mixture into balls and flatten them into patties. Press sesame seeds into each patty if desired.

Heat olive oil in a skillet over medium-high heat. Cook the patties for about 5 minutes on each side until golden brown and crispy.

Mix chopped tomatoes with salad onions in a bowl. Spread hummus on each sandwich roll, layer the tomato/onion mixture, fresh greens, and 2 to 3 falafel patties. Drizzle with Greek yogurt before closing the sandwich.