Blanche spniach in large pot for 2 miutes. Drain in cool water, squeeze out excess water and chip. In large pan, saute onions and serrano in butter & oil until brown. Puree in food processor the ginger and garlic then add to onions, simmer 10 minutes. Add spices and tomatoes, simmer 5 minutes. Add spinach and peas, simmer 30 minutes, adding water as needed. Garnish with lemon juice.