Heat the oil in a large pot over medium heat until shimmering Add the onion and cook for 2-3 minutes.
Add the garlic, ginger, chilies and salt and cook for another 2-3 minutes.
Add the ground cumin, coriander, chili powder, turmeric and garam masala. Stir to coat.
Next, add the tomatoes and chickpeas. If the mixture looks too thick, add up to 1 cup of water. The goal is for a semi-thick soup.
Increase the heat to medium-high until it reaches a rolling boil then reduce to medium-low and maintain a simmer (uncovered) for 15-20 minutes, or until thick and stew-like. Stir occasionally.
Remove from heat and add lemon juice. Stir to combine, then allow to cool slightly before serving.