Heat the oil in a large pan over a medium-high setting. Sauté the finely chopped onion until golden.
Add the crushed garlic and grated ginger and cook for 1-2 minutes, stirring frequently, until the garlic doesn't smell raw anymore.
Mix in the next four ingredients (ground coriander, turmeric, cumin, and cayenne) and toast for two minutes stirring often.
Add the crushed tomatoes, chickpeas and vegetable stock. Increase the heat to high and once boiling, lower to medium-low to maintain at a simmer for 10 minutes, stirring every now and then.
Add ½ tsp salt, the sugar, and the spinach. If the spinach is frozen increase the heat until the curry is bubbling away again. Simmer for an additional five minutes.
Add the garam masala, lemon juice and coconut milk and stir. Sprinkle over the chopped cilantro leaves and serve hot.
