In large bowl, whisk together the peanut butter, warm water, soy sauce and vinegar until smooth. Stir in the garlic and scallion. Add chicken and stir until coated.
Place one wrap or tortilla on a flat work surface. Scatter one-fourth each of chicken, red pepper, cucumber and bean sprouts over the top. Tightly roll up from one narrow end. Cut in half on the bias. Repeat with the remaining ingredients to make 4 wraps.