Preheat oven to 350 degrees Fahrenheit. Cut off the top third of pumpkins, scoop out seeds, and place cut side down on baking pan. Place lids face down in the pan as well. Add a quarter-inch water to pan and bake for approximately 45 minutes (depending on size of pumpkins), or until soft.
Heat oil in a sauté pan over high heat. Add onions and sauté, stirring every few minutes. Do not stir constantly as this will not allow the onions to caramelize. Do not salt the onions before sautéing either, as this will cause them to release their juices and they won’t caramelize well.
When halfway done, add the potatoes. Sauté for about three minutes, then add apples. Sauté until soft. Cut the pastrami into strips and add to pot. Heat until warm. Season with nutmeg, salt and pepper.
To assemble, place warm pumpkin on plate and generously fill hole with filling. Position lid sideways, leaning on pumpkin.