In large pot with 1 cup water at the boil add spinach, press down to allow it to fit, toss often until just wilted...do not cook too long.
Toss spinach and water into food processor or vitamix, process until smooth, set aside
In a large pot or wok, add oil and all spices, cook for 2 minutes, then add onions, ginger and garlic.
Cook onions and garlic for 10 minutes stirring often then add tomatoes and turmeric, cook 1 minute more.
Add spinach mixture and stir to heat up spinach and combine with spices and aromatics.
Add potatoes, warm them up and serve.
Do not cover the pot as the spinach will tend to lose it's vibrant green color.