First of all thaw the frozen spinach, either using the microwave or by just putting it in the sun. In the meantime peel and finely chop onions and garlic. In a sauce pan heat sunflower oil at medium – high, throw in onions and sauté for 3 minutes. Add garlic and sauté for another minute. Stir in tomatoes and 1 tablespoon of water. Cover and let simmer for 5 minutes.
Once spinach is thawed, use your hands to squeeze out the water. Add it to the pot, combine well, cover and let simmer for 5 minutes. Then stir in the remaining water and let simmer for another 5 minutes. Season with salt, pepper and a pinch of nutmeg. Cook for another minute, uncovered, remove from the heat and serve immediately.