To Make The Filling:

1. Heat oil in a large saute pan over medium-high heat. Add the mustard seeds and fry for about ten seconds, or until they begin to splutter.
2. Add the onion and ginger, and saute for 2 to 3 minutes, stirring occasionally. Add the peas, coriander, cumin, chili powder, garam masala and salt. Cook for 2 minutes, stirring occasionally. Then add the potatoes and cilantro, stir to combine, and cook for another 2 minutes. Add a few splashes of water (this may be more or less than 1/4 cup) until the mashed potatoes are slightly moist. Taste the mixture and adjust the seasoning as necessary, then remove from heat.

To Make The Phyllo Dough Triangles:

1. Preheat oven to 400 degrees F.
2. Unroll the phyllo pastry dough, cover with plastic wrap and a damp lightweight towel. Peel off one sheet and keep the remaining dough covered so that it doesn’t dry out. Lay the pastry sheet flat on a clean surface, and brush lightly with melted butter. Fold in one third of the pastry lengthwise towards the middle. Brush again with the butter and fold in the other side to make a long triple-layered strip.
3. Place one rounded teaspoon of the filling mixture at one end of the strip. Take the right corner and fold diagonally to the left, enclosing the filling and forming a triangle. Fold again along the upper crease of the triangle. Keep folding in this way making triangles upon triangles until you reach the end of the strip. Brush a little butter on the dough to seal the samosa, and also brush the outer surface so that the outside is lightly coated in butter.
4. Place the triangle onto a baking sheet and cover with another damp towel while you make the rest of the samosas. Bake in the center of the oven for 20-25 minutes, or until golden and crisp, turning halfway through the cooking time.
5. Serve warm, garnished with extra chopped fresh cilantro if desired.

To Make The Mini Phyllo Cups:

1. Spoon about 1 rounded teaspoon of the filling into each mini phyllo cup. You can either serve these immediately, or pop them in a 400-degree oven for a few minutes to warm them up if need be. Serve garnished with extra chopped fresh cilantro if desired.