1 1/2 cups water
1 1/2 cups chicken broth
2 large carrots, peeled and cut into 1/4-inch slices
1 large onion, cut into 1/8-inch slices
1 teaspoon salt
1 teaspoon dried oregano
8 boneless, skinless chicken tenderloins
Place chicken in a slow cooker. Add broth and carrots; cover and cook on Low for 4 to 6 hours.
Meanwhile, in a large bowl, combine rice wine vinegar, salt, oregano, chicken and salt. Mix well and gradually stir chicken into this mixture. Add vegetables; pour into cooker. Add chicken, coating well. Reduce heat and simmer on Low for 8 hours.
Remove chicken from broth and tenderloins and chop into pieces.
Cook on High for 3 to 5 hours per inch of thickness of chicken, or add more water or broth to cover.