In a serving bowl, toss together the oil, dill, zest, salt and pepper and tomatoes. Let stand at least 10 minutes, or while you cook the orzo.
Bring a pot of well-salted (1 ½ tablespoon: 4 quarts) water to a boil. Stir in the orzo and cook just until it is tender to the tongue. Drain the orzo and into with the tomato dill mixture. Add the feta and toss again.