
Combine chicken broth, salt, and pepper in a large soup pot; bring to a boil over high heat. Cut chicken into 3 equal parts and put into broth for 12 minutes off heat. Remove chicken. Return to boil. Add carrots, fennel, and orzo; return to a boil. Reduce heat to low and simmer, partially covered, until orzo and vegetables are tender, 8 to 10 minutes. Stir in chicken; cook until heated through, about 5 minutes.
Remove pot from heat; stir in lemon juice and dill.