1Combine the jalapeño peppers, lemongrass, cilantro, garlic, lime juice, oil and ginger in a blender and pulse until you have a sort of paste.
2Add a drizzle of oil to a large skillet and set it over medium-high heat. Add the tomatoes and cook for a few minutes, until they release some of their juices and start to brown and soften. Add about half of the green spice paste and cook for another minute. (The rest can be set on the table as a condiment, kept in the fridge or frozen for another meal.)
3Pour in the coconut milk and bring to a simmer. Cook for a minute or two, to allow it to thicken a bit. Add the shrimp and spinach and cook for about 2 minutes, until the spinach wilts and the shrimp turn opaque. Remove the pan from the heat immediately, so that you don’t overcook the shrimp. Season with salt to taste and serve immediately over rice.