Peel and wash sweet potatoes and carrots and cut into cubes or slices. Peel and finely chop onions, garlic and ginger.
Heat 2 tablespoons of oil in a large pot. Briefly sauté onions, garlic and ginger in it, add approx. 1⁄4 diced sweet potatoes and fry briefly. Peel and chop the banana and add it as well. Sprinkle with 1-2 teaspoons curry. Deglaze with coconut milk and 600 ml water, bring to the boil. Stir in stock and simmer for about 10 minutes while stirring.
Finely puree the curry with a hand blender, then add the carrots and remaining sweet potatoes and cook for another 10-12 minutes at medium heat.
In the meantime clean, wash and dice the eggplant. Roast the coconut chips in a pan without fat until golden brown, take them out. Heat the remaining oil in the pan. Sauté the aubergine in this oil for 3-5 minutes. Season with salt and pepper. Add the aubergine shortly before the curry is done. Season to taste with salt, pepper, lime juice and sugar. Sprinkle with coconut chips and cress as desired.