1. Preheat oven to 425°. Put turkey breast in a 9- by 13-in. roasting pan and rub with olive oil. Sprinkle all over with 1/2 tsp. salt and 1/2 tsp. pepper and rub in evenly. Roast turkey until the thickest part of the breast reaches 160°, about 70 minutes. Remove from oven and let sit until cool enough to handle, about 20 minutes. Remove and discard skin, then cut meat into 1/2-in. dice (you will have about 3 cups turkey).
2. Meanwhile, whisk together mayonnaise, sour cream, lime zest, lime juice, chives, and remaining salt and pepper.
3. Put turkey, avocados, cherry tomatoes, and bacon in a large bowl; stir gently to combine. Add lime-mayonnaise dressing and stir to evenly coat filling.
4. Spoon sandwich filling onto 4 or 5 slices of bread and top with remaining slices. Cut each in half and serve.
Note: Nutritional analysis is per half-sandwich.