In a large pot, heat the oil over medium heat. Add the onion and mushrooms and cook for about 3 minutes, until translucent.
Add the garlic and cook for 3 minutes, until golden. If using additional veggies (celery, carrot, cauliflower, broccoli), add now and cook until softened.
Add the tomato paste, ginger, salt, mustard, coriander, curry powder, cumin, and chili flakes. Stir and toast for 30–60 seconds, until fragrant.
Stir in the coconut milk, diced tomatoes, and chickpeas. Cook uncovered for 5 minutes, until slightly thickened.
Stir in the kale and tahini (if using), and cook for about 2 minutes, until wilted. Finish with a squeeze of lemon or lime juice.
Serve in bowls with warm rice, roasted potatoes, or naan, and any of the garnishes below. Enjoy!