Bring a large pot of salted water to a boil. Add the vermicelli and cook until almost tender, about 3 minutes. Drain and rinse under cold water to cool. Drain the noodles very well, tossing with tongs to release as much water as possible. Snip the noodles with scissors a few times to cut the long strands.
Bring the chicken broth and 2 1/2 cups water to a simmer in a medium saucepan. Whisk in the peanut butter, soy sauce and Sriracha. Then add the chicken and bell pepper. Cook, over medium-low heat, at a bare simmer until the chicken is just cooked through, 3 to 5 minutes. Add the cooked rice noodles and scallions to the soup. Divide among 4 bowls and top with the cilantro, cucumbers, romaine and serve with lime wedges.
This recipe has been updated to more accurately recognize its origin or to add cultural context. It may differ from what was originally published or broadcast.
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