Preheat oven to 350°F. Using a small sharp knife, cut a 4-inch circle around the pumpkin’s stem. Cut off any stringy membrane attached to top; set aside. Use a large spoon to scrape and remove seeds and stringy membrane from inside pumpkin. Set pumpkin on a parchment paper– or aluminum foil–lined rimmed baking sheet. Add rice, coconut milk, 1/4 cup water, and curry paste to pumpkin; stir to dissolve curry paste. Place top on pumpkin. Bake pumpkin in preheated oven until filling is bubbling, about 1 hour. Carefully remove top, and stir in green beans, fish sauce, and salt to taste. Replace top, and bake at 350°F until pumpkin flesh and green beans are fork-tender and rice has a risotto-like texture, 30 to 45 minutes. Let stand 15 minutes; taste and adjust seasoning with salt or fish sauce. Scoop rice and tender pumpkin into bowls, and top with cilantro, mint, and fried shallots.