In a small saucepan, combine the tamarind concentrate, sugar, salt, ground cumin, ground coriander, cayenne pepper (if using), and water.
Bring the mixture to a boil over medium heat, then reduce the heat and simmer for about 10-15 minutes, or until the sauce thickens to your desired consistency.
Remove from heat and let it cool. Set aside.
In a large bowl, combine the all-purpose flour, chickpea flour, baking powder, ground turmeric, ground cumin, ground coriander, salt, and sugar.
Add the minced garlic and finely chopped onion to the dry ingredients.
Gradually add the warm water to the mixture, stirring constantly to form a thick, smooth batter. The batter should be thick enough to hold its shape when dropped from a spoon.
Cover the bowl with a damp cloth and let the batter rest for about 30 minutes.
Heat vegetable oil in a deep frying pan or pot over medium heat.
Using a spoon or your hands, drop small portions of the batter into the hot oil. Fry the pholourie in batches, being careful not to overcrowd the pan.
Fry until the pholourie are golden brown and cooked through, about 2-3 minutes per side.
Use a slotted spoon to remove the pholourie from the oil and drain on paper towels.
Enjoy your meal!