Start heating a large pot of water to boiling for the pasta. On a plate, combine the flour, 1/4 tsp. of the pepper, and salt. Dredge the chicken in the flour mixture, shaking off the excess. In a large nonstick skillet, heat the oil until hot but not smoking, over medium heat. Add the chicken and cook, stirring frequently, until golden brown, about 4 minutes. With a slotted spoon, transfer to a plate.
Add the garlic, zucchini and bell pepper to the pan and cook, stirring frequently, until the bell pepper is tender, about 5 minutes. Sprinkle the vinegar over the vegetables. Stir in the tomato, 1/2 cup of water, dill, oregano, and remaining 1/4 tsp. of pepper.
Bring to a boil over medium high heat, reduce to a simmer, cover, and cook until the mixture is flavorful and slightly thickened, about 4 minutes. Add the chicken and cook, uncovered, until the chicken is cooked through, about 1 minute longer. Remove from the heat & stir in the sour cream.
Meanwhile, cook the radiatore in boiling water until just tender. Drain well. Transfer the chicken mixture to a large bowl, add the radiatore, and toss to combine. Add the feta cheese and toss again.