Heat the oil in a pan over medium heat until warm but not smoking.
Add the cumin seeds and garlic paste, then sauté briefly until aromatic and lightly sizzling.
Stir in the onion and cook for several minutes until soft, translucent, and lightly golden.
Add the chicken and cook, stirring regularly, until it changes colour and begins to firm up.
Mix in the potatoes and continue cooking so they start to soften slightly.
Sprinkle in the chilli flakes, salt, coriander powder, and chilli powder, then stir well to coat everything evenly and allow the spices to cook out.
Pour in enough water to create steam, cover the pan, and cook gently on low heat until the chicken is fully cooked and the potatoes are tender.
Remove the lid, stir through the fresh coriander, and cook briefly until any excess moisture evaporates and the filling is thick and dry. Set aside to cool.
In a small bowl, mix the plain flour with enough water to form a smooth, lump-free paste for sealing.
Take a spring roll sheet, form it into a cone, and seal the edge with the flour paste.
Spoon the cooled filling into the cone, fold into a neat triangle, and seal the final edge securely with more paste.
At this stage, the samosas can be frozen for later use if desired.
Heat oil for deep frying until hot, then carefully lower the samosas in and fry gently until golden and crisp on one side.
Turn them over and continue frying until evenly golden and cooked through.
Remove and drain on kitchen paper before serving.
