Begin by preparing the dough. In a large mixing bowl combine flour, salt and oil and mix with your fingers until it resembles coarse bread crumbs. Add water and mix with both hands until fully combined and mixture holds as a ball. Turn out onto a clean flat surface and knead for 10 minutes until the dough becomes smooth. Flatten into a disc shape and set back in bowl and cover with plastic wrap to rest for 30 minutes while you prepare the filling.
Set a large, heavy-based pot over medium-high heat and add vegetable oil. Add spices and stir until just fragrant - this lightly toasts the spices and forms the spicy base of the filling mixture. Add ground chicken and saute until slightly coloured. Add onion, garlic, and ginger and sweat. Add chickpeas and spinach then simmer for 10 minutes until liquid has evaporated and all the flavours have come together. Season with salt and pepper. Set aside and allow to cool (you can pour it out onto a flat platter to speed up the cooling process.
Return to the dough and divide it up into 4 equal parts. Working with one piece at a time roll into a nice ball then using a rolling pin roll out into discs. Cut in half down the middle to form two half-circles. Working with one half at a time, rub a little water around the edges using your finger. Form a cone by folding along the straight edge overlapping the seam. Gently pinch at the fold to secure. Holding the cone in your hand fill with 2 tablespoons of filling. Seal the top by bringing the edges together and crimping with your fingers or a fork. Do this with the rest to make 8 samosas. (note: you can freeze them at this point if you wish).
Heat vegetable oil to 360 degrees F in a large heavy-based pot. Fry the samosas in batches (so as to not to over-crowd the pot) until puffy and golden. Remove with a slotted spoon and drain on paper towels. Season with salt and serve with Raita.
Combine ingredients in a food processor and pulse 3 times to just chop up the cucumber. The raita should be nice and creamy from the yogurt but still have texture from the cucumber.