Saute ginger, onion, chiles and lemon grass until soft. Deglaze pan with fish sauce. Add chicken stock and lime leaves. Simmer and reduce the liquid by 20 per cent. Add vinegar, basil and pepper. Check for seasoning. Strain the soup. Add sauteed shiitakes and fresh enoki mushrooms. Ladle soup in soup plates. Garnish with shrimp toast and scallions.
In a food processor, puree first 5 ingredients. Check for seasoning. Fold in scallions, cilantro and jicama. Spread the mixture on bread, cut in half on the diagonal and sprinkle with sesame seeds. Heat a deep fryer to 375 degrees F and fry until golden brown.