Reserve cilantro leaves for garnish. Place cilantro stems in a food processor and add chile peppers, lime zest, lemongrass, ginger, garlic, five-spice powder, and cumin. Blend to a pulp; remove and discard any stringy bits and transfer mixture to a high-sided skillet. Add olive oil and white onion. Cook and stir over medium-low heat until fragrant, about 10 minutes.
Add pumpkin and broth to the skillet. Stir around, scraping up any bits stuck to the bottom of the skillet. Bring to a boil; reduce heat and simmer, covered, until pumpkin is soft, about 15 minutes. Add rice and stir well so that pumpkin gets mashed up a bit. Cover and simmer until rice is tender, 15 to 20 minutes more. Add coconut milk and season with salt and pepper. Stir in lime juice to taste. Garnish with reserved cilantro leaves, green chile pepper, and grated coconut.
