Place walnuts and sunflower seeds in a dry frypan over medium heat. Cook, stirring occasionally until lightly toasted and fragrant, about 5 minutes.
In a medium bowl mash chickpeas with a fork or chop in a food processor. Stir in the onion, egg, parsley and toasted nuts. Season with pepper and seasoning blend and mix well.
Heat olive oil in a frypan over medium heat. Divide the bean mixture into 2 patties and fry in the hot oil for about 3 minutes on each side or until well browned and heated through. Place a slice of cheese over each patty and remove from heat.
Place the pita bread in the same dry frypan the nuts were in and heat for about 1 minute on each side. Cut the bread in half, spread ranch dressing inside of each and line the pockets with cos leaves. Place a cheesy patty into each one and top with sliced tomato and avocado. Serve with potato chips.