In a Dutch oven or other large pot with a lid, heat oil over medium-high heat. Add the chopped onion and ginger and cook, stirring now and then until they start to soften and turn gold, about 5 minutes. Add minced garlic and cumin, coriander and turmeric. Continue stirring and cooking another few minutes, or until all the vegetables are gilded in the spiced oil.
Add tomatoes, all your greens, and water or broth. Mix together well. When the pot comes to simmer, cover, reduce heat to low and let everybody cook for about 15 minutes, until greens are softened, with a flavor that sings of their greenness. If they’ve thrown off a lot of liquid, continue cooking a few minutes more with the lid off, stirring occasionally, so any excess liquid cooks away.
Turn off the heat, add lemon juice and season generously with sea salt and pepper. Sprinkle in chopped cilantro, if using, stir and serve.