Heat 1 teaspoon vegetable oil in a pan over medium heat. Add chopped onion and cook until soft and translucent.
Add peas, carrots, green chilies, salt, and black pepper. Cook for 2 to 3 minutes until the vegetables begin to soften. Remove from heat.
In a large bowl, mash the boiled potatoes until mostly smooth with a few small chunks remaining.
Add the spice mix to the potatoes along with the cooked vegetable mixture, lemon juice, and chopped cilantro. Mix well until evenly combined.
Take a samosa wrapper, fold it into a cone shape, and fill with 2 to 3 tablespoons of the prepared filling. Seal the edges using the flour paste. Repeat with remaining wrappers.
Heat vegetable oil in a deep frying pan over medium-high heat.
Carefully add the samosas in batches and fry until golden brown and crisp, turning occasionally. This takes about 3 to 4 minutes per side.
Remove using a slotted spoon and drain on paper towels. Serve hot with chutney or your favorite dipping sauce.