This colorful orange squash hors d'oeuvre soup offers beautiful contrast to the bright-green chilled spinach-pea soup hors d'oeuvre and beet soup hors d'oeuvre.
Heat the olive oil in a large pot over medium heat. Add onion, season with salt, and cook, stirring occasionally, until softened, 5 to 7 minutes.
Add squash, stock, and enough water to cover (4 to 5 cups). Bring to a boil. Reduce heat to medium, and simmer until squash is tender and can be pierced easily with the tip of a paring knife, about 20 minutes.
Puree stock and vegetables in a blender until smooth. (You may need to work in batches.) Transfer pureed soup to a clean pot, and adjust consistency with water if necessary (you should be able to drink soup easily without using a spoon). Season with salt, pepper, and lemon juice. Use a glass measure to pour soup into 2-ounce sake or espresso cups, and serve warm.