Bring a medium saucepan of lightly salted water to a boil. Stir in potatoes and peas. Cook until potatoes are tender but still firm; about 15 minutes. Drain, mash together and set aside.
In a large saucepan over medium high heat, heat 2 tablespoons oil and brown cumin seeds and bay leaf. Add onions and minced beef and cook, stirring until onions are soft and beef is evenly brown, about 5 minutes. Add garlic, ginger, pepper, salt, cumin, coriander, turmeric, chilli powder, cinnamon and cardamom and mix well. Stir in the mashed potato mixture, then remove from heat and chill in the refrigerator for 1 hour, or until cool.
Heat oil in a large, heavy saucepan over high heat.
Mix coriander and green chillies through the potato and beef mixture. Cut the filo sheets into 9x30cm strips. Use two strips at a time, keeping the rest covered with a clean damp cloth. Place about 1 tablespoon of the mixture on to the bottom corner of the 2 stacked filo strips and fold the end of the pastry over the filling making a triangular shape. Continue folding up the strip to the top, alternating diagonal and straight folds, and press edges together with moistened fingers.
In small batches, fry samosas until golden brown, about 3 minutes. Drain on paper towels and serve warm.