To make the pastry, stir flour and salt in a large bowl. Add the light olive oil, rub in with your fingers, then gradually add just enough cold water to bring it together into a stiff dough – about 1/3 cup. Knead for 5 minutes until smooth, then lightly oil, cover and set aside to rest.
Meanwhile, for the filling, heat the olive oil in a frying pan over medium heat. Fry onion, chilli and ginger for 4 minutes or until soft and golden. Sprinkle over spices and cook for 1 minute. Stir in carrot and cook for 2 minutes until softened. Add potato and 1/4 cup water. Bring to the boil. Simmer for 4 minutes or until tender. Add peas. Transfer mixture to a bowl and cool. Stir in paneer and lemon juice. Season. Finely chop coriander and stir into mixture.
Divide pastry into 12 pieces, approximately 20g each. Work with 1 piece at a time and cover remainder with a damp cloth. Roll out on a lightly greased surface until 12cm across. Cut in half, wet the straight side with a little water and form into a cone shape, overlapping the edges. Press edges together well to seal.
Spoon 2 tsp vegetable filling into shell. Dampen the top edge and pinch to close. Repeat with the remaining pastry and filling.
Pour oil into a medium saucepan until 1/3 full. Heat over medium-high heat until a small piece of bread sizzles when added. Cook samosas, in batches of 6, for 2-3 minutes, turning until golden on all sides. Transfer to a tray lined with paper towel.
To make sauce, finely chop half of the mint and mix with yoghurt. Season. Serve samosas garnished with remaining mint leaves and yoghurt sauce.