In 2-quart saucepan, combine red onion and vinegar. Bring to a boil, cook, stirring occasionally until vinegar is almost evaporated, 4 to 6 minutes. Cool, chill.
Combine, yogurt, lime juice, jalapeno, green onion, cilantro, salt, black pepper and garlic. Stir to mix well.
Stir in chicken and avocado. Set aside.
To make tortilla straws, heat oil in a deep 10-inch skillet or 3-quart saucepan to 365°F. Add corn tortilla strips in batches and fry until golden brown and crisp. Drain. Cool.
Layer over each flour tortilla: Romaine, red pepper strips, tortilla straws, pickled onions and chicken mixture. Fold lower third of tortilla over filling, fold in right and left edges of tortilla, about 1-inch on each side. Roll wrap closed.