Samosas: Place potatoes in large pot covered with water.Bring to a boil, then reduce to simmer and cook until fork tender, about 20 minutes. Drain and let cool. When cooled, finely dice.
Heat 2 Tbsp. canola oil over medium heat. When oil is hot add cumin seeds and cook until they start to make a popping sound. Add red onion and cook to soften. Add the potatoes, coriander, tumeric, salt and cayenne and continue to cook for 3-4 minutes, stirring occasionally.
Transfer mixture to a bowl and add peas, ginger, sugar, fresh cilantro and lime juice. Mix well with a fork to incorporate all ingredients. Set aside to cool.
Line a large baking sheet with paper towels and set aside.
In a small bowl, whisk together flour and some water to make a thin paste.
Keep pastry sheets covered with a damp paper towel to prevent drying out.
Fill and fold the samosa pastry sheets with a teaspoon or so of the potato mixture, sealing the last fold with the flour paste to seal.
Fill a heavy, deep skillet with about 2 inches of canola oil and heat over medium low heat. Fry samosas in batches (being careful not to crowd the skillet) for 2 minutes each side or until lightly browned. If they are browning too quickly, reduce heat.
Remove from skillet with slotted spoon to prepared sheet.
Serve with chutneys.
Mango Chutney:
Combine sugar and vinegar in a large 5 quart pot. Bring to a boil until sugar dissolves, stirring often.
Add remaining ingredients. Simmer, uncovered until the mixture thickens, about 45 minutes to 1 hour. Remove from the heat and let cool. Store in glass jars.
Peanut Cilantro Chutney:
Puree all ingredients in a food processor until smooth.