For the pastry: Combine the flour, salt, cumin seeds, and oil, in a medium bowl. Mix until the oil is evenly distributed. Mix in the water, and knead for 2 to 3 minutes, or until it is smooth and has the consistency of bread dough. Set aside while you prepare the filling.
For the filling: In a large bowl, add the chickpeas, brown rice, cranberries, garam masala, tamarind pulp, coriander, chile flakes, ginger, cumin seeds, and salt, to taste, and mix until the garam masala is evenly distributed.
Preheat the oven to 425 degrees F.
Divide the dough into 4 pieces and roll each into a smooth ball. Using your hands, form each ball into a flat disk. Dust a working surface with flour so the dough doesn't stick, and using a lightly-floured rolling pin, roll a disk into a thin patty (like a tortilla) and cut the circle in half. Take one of the half circles and make a cone shape starting at the center of the cut side to make the point of the cone and then wet the edges with a little water to glue the overlapping the edges together. Put 1/3 cup of filling into the cone, moisten the top of the inside edges and close the cone, pressing the edges to seal it. Brush with grapeseed oil on each side of the samosa and then place it on a baking sheet. Repeat the process to make 8 samosas. Place the samosas in the oven, and bake for 20 to 25 minutes, or until the samosas are nicely browned. Serve with the Tamarind Chutney.
Combine the tamarind pulp and warm water in a bowl, and let it soak for 10 minutes. Use a fork to separate the seeds and the pulp. Strain the mixture into a bowl, using a rubber spatula to force it through the sieve, and then mix the strained pulp with the brown sugar, coriander, and salt, and pepper, to taste, until combined.