Place chicken breasts in a large pot of water over high heat. Bring to a boil, cooking for 30-40 minutes until chicken is cooked through and easy to shred.
Drain chicken, reserving a tablespoon or so of water.
Add water back to the pot, along with the shredded chicken and taco seasoning; stir until the chicken is well coated with seasoning.
Dice tomato; shred lettuce and cheese (if needed).
Layer tortillas with chicken, lettuce, tomatoes, cheese, and sour cream as desired.
Serve with orange slices on the side.