In 12 inch skillet over medium high heat, in hot salad oil, cook chicken until browned on all sides. Remove from skillet. Add mushrooms and garlic to drippings in skillet. Cook about 2 minutes. Stir in flour until blended. Gradually stir in sherry, bouillon, salt and water. Cook, stirring constantly, until mixture is slightly thickened.
Add chicken, heat to boiling. Reduce heat to low. Cover and simmer 30 minutes, stirring. Meanwhile, cut half of a cucumber into very thin slices, set aside for garnish. Peel remaining cucumbers and cut into large chunks. Add cucumber chunks to chicken and continue cooking 15-20 minutes or until chicken is fork tender and cucumber is tender-crisp. Stir in sour cream. Cook until heated through, but do not boil. Arrange chicken pieces on warm platter, surrounded with chunks of cucumber and pour on sauce. Garnish with cucumber slices.