In a large non-stick pan heat the canola oil over a low heat cook the onion for 3 min, then add the ginger, garlic and peas and 1 tbls of water, cook while stirring for 4 min.
Then add the chilli, cumin, coriander, salt, turmeric, potato and 2 tbls water, cook for a further 4 min adding more water if required.
Then stir in the chopped fresh coriander, lemon juice and garam masala, set aside to cool before making up your samosas.