In a pan, heat olive oil and add onion, ginger and garlic. Saute till the onion becomes soft and translucent.
Add turmeric powder, red chilly powder, cumin powder, coriander powder, curry powder and fry for 1-2 minutes. Set aside to cool.
In a food processor, add chickpeas, oats, green chillies, coriander leaves, lemon juice and process until well combined. Transfer the mixture to a bowl.
Add the onion mixture, salt and mix well. Divide into 4 balls and shape into patties. Place on a plate and put in the fridge for at-least 30 minutes.
Heat a frying pan with oil and place the chickpea patties. Cook for 4-5 minutes on each side or till they turn golden brown.
To make sauce
In a bowl, add the yogurt and whisk well. Add the tahini paste, lemon juice, salt, pepper and mix well.
To assemble burger
Slice the burger buns and toast the buns if desired. Place lettuce leaves, tomato slices, onion slices and cucumber slices.
Place a patty and top with 1-2 tbsp of yogurt-tahini sauce. Cover with the other half of the bun and serve immediately.
Notes
Process the chickpeas and other ingredients until just combined. Do not make a paste.
Add more powdered oats if you feel the patty mixture is watery.
Adjust spices according to your taste preference.
Refrigerating the patties will make them firm and avoid crumbling.
Drain water completely after cooking the chickpeas. If using canned chickpea, wash well and drain.
Tahini is a Middle Eastern paste made from white sesame seeds