I did the dough in a food processor which is easy! Combine flour and sea salt. Pulse in cold, cubed vegan butter until it is fine crumb texture. Pulse in the nondairy milk until a ball begins to form. Don't over process. As soon as the dough comes together, stop.
Dump the dough onto a large sheet of plastic wrap. Knead a couple of times until the dough comes together. It should only take 2 to 3 folds/kneads. Then wrap the plastic over top and gently flatten and shape it into a thick round, cover with the rest of the wrap, and refrigerate for 30 minutes or make ahead and refrigerate for up to 24 hours.
Preheat oven to 425°F.
To make the filling, fill a small pot with water. Bring to a boil with potatoes and carrots and cook until tender, about 10 minutes. Be sure to drain from the water to prevent over cooking.
In a large skillet, heat oil over medium heat. Then add the fennel, cumin, mustard, coriander, turmeric, garam marsala, fenugreek and cayenne. Stir together and coat in oil and listen for the seeds to begin to pop, about 1 minute.
Then add onion, garlic, ginger and sea salt. Lower heat if necessary to prevent burning. Fry until softened, about 3 to 4 minutes.
Then stir in potato mixture and peas. Continue cooking for 5 to 7 minutes.
Stir in lemon juice and coriander for about 1 minute. Then remove from heat and set aside while you roll out the pastry.
If you've let your dough sit in the fridge overnight, you might need to let it sit at room temperature for 5 to 10 minutes before rolling out. It should be cool and firm, but not super cold and tough to maneuver.
Place the dough on a lightly floured surface. Cut the round in half, then quarters, then eighths. Gently roll those pieces into balls of dough. Gently pat it down to form a flatter circle and using a rolling pin, roll until it's just over ¼-inch thick. Ensure you have extra flour standing by to flour the surface and rolling pin to prevent sticking.
Cut the round in half. Fill each half with about 1 ½ tablespoons of filling. Fold over to make a triangular shape. Then seal the edges by pinching the side seam. You can also use a bit of water on the inside flaps to allow the dough to stick together. Fold the excess on the bottom onto itself and use a fork to seal.
Place all the samosas onto a parchment lined baking sheet. Spray with a light coating of oil and bake in for about 25 minutes until golden brown.
NOTE: I have not tried deep frying these! If you do, let me know the results.
Make the mango chutney while the samosas are baking.
In a medium saucepan, combine all of the ingredients. Bring the mixture to a slow boil over medium high heat, stirring occasionally. Once bubbling, lower heat and simmer for approximately 30 minutes, uncovered, stirring occasionally. The consistency should be thick and glossy and none of the orange mango colour should be coming through!