In a small food processor or bullet, puree the onion, garlic and ginger into a paste. Set aside.
Heat oil in a large pot on medium high heat and add carrots and cauliflower. Cook, stirring occasionally, until vegetables start to soften and get some colour, about five minutes.
Turn down heat to medium and season with salt and pepper.
Add onion puree, and heat through for 1-2 minutes, stirring constantly so it doesn't burn.
Add vegetable stock and water, along with turmeric, curry powder, salt, cumin and garam masala. Stir to combine and add chickpeas.
Let soup simmer for at least 15 minutes so flavours can develop. When finished, stir in lemon juice, taste and adjust seasoning if desired