Cook noodles, drain, and set aside.
In a large bowl, combine peanut butter, 1/4 cup water, soy sauce, vinegar, chili paste, and sugar. Whisk until blended. If sauce doesn not have the consistency of cream, thin it with a little water.
Add noodle, bell pepper, cucumber, and green onions to the bowl. Toss well, and sprinkle with cilantro.

8 ounce linguini or rice noodle
1/3 cup creamy peanut butter
2 tablespoon rice wine vinegar
1 tablespoon soy sauce
1 tablespoon garlic chili paste
1/2 teaspoon brown sugar
1 red bell pepper, cut into thin slices
3/4 cup chopped seeded cucumber
3 green onions, cut into slices
2 tablespoon fresh cilantro, chopped
filtered water