Preparation Heat oil in a 4-quart wide heavy pot over moderately high heat until hot but not smoking. Add onions and salt, then reduce heat to moderate and cook, stirring occasionally, until golden, 15 to 20 minutes. Reserve 1/4 cup onion. Add turmeric to onions in pot and cook, stirring, 1 minute. Add water and bring to a boil. Add linguine and boil, uncovered, until tender, about 10 minutes. Stir in chard and beans and simmer, stirring occasionally, until chard is tender, about 5 minutes. Remove from heat. Stir in herbs, scallion greens, and salt and pepper to taste. Serve soup topped with reserved onion.
Preparation Heat oil in a 4-quart wide heavy pot over moderately high heat until hot but not smoking. Add onions and salt, then reduce heat to moderate and cook, stirring occasionally, until golden, 15 to 20 minutes. Reserve 1/4 cup onion. Add turmeric to onions in pot and cook, stirring, 1 minute. Add water and bring to a boil. Add linguine and boil, uncovered, until tender, about 10 minutes. Stir in chard and beans and simmer, stirring occasionally, until chard is tender, about 5 minutes. Remove from heat. Stir in herbs, scallion greens, and salt and pepper to taste. Serve soup topped with reserved onion.