In a bowl, mix together the turkey mince, spring onions, spinach, carrot and cumin. Season and shape into 4 equal-sized patties, each slightly smaller than the burger buns. Transfer to the fridge and chill for 30 minutes to firm up.
Set a frying pan with the sunflower oil over a medium heat. Fry the patties for 15 minutes, turning halfway, until cooked through. Top each patty with a slice of cheese for the last 5 minutes’ cooking time.
To assemble the burgers, cut the buns in half and fill with the lettuce, turkey patties, sliced tomato and onion rings.