Cut the tofu into cubes or small chunks. Drizzle with oil, then toss with garam masala, turmeric, cornstarch, and salt until well coated.
Spread out evenly on a lined oven sheet and bake for 15 minutes, then flip and bake for another 5-10 minutes or until golden brown.
To Make the Curry
While the tofu is baking, blend the mango and water until smooth, and set aside.
Heat the oil in a large pan, add cumin seeds, fennel seeds, and cinnamon stick, and cook for 1 minute over medium-high heat without burning them. Add the ginger and garlic, stir fry for 1 minute, then add coriander, ground cumin, turmeric, and chili powder, and stir-fry for another 30 seconds.
Add the mango puré, coconut milk, garam masala, and salt, and stir well. Let simmer for 10 minutes, stirring occasionally. Add some water if needed.
Assemble and Serve
Add spinach, coriander, and lime juice. When spinach is just wilted, add tofu, stir well and adjust seasoning (salt/lime/chili) to taste if needed and then remove from heat.
Serve with Basmati rice and/or Indian naan and top curry with coriander leaves, vegan yogurt, and nigella seeds.
To press tofu, use a tofu press or place tofu in a shallow bowl or plate, place an inverted plate on top and a heavy object on top. If pressing overnight, place in the fridge.