Combine the olive oil and the orange zest in a small bowl and set aside.
For the salad:
Bring the large saucepan of chicken broth to a boil over high heat. Add the fregola pasta and cook until tender but still firm to the bite, stirring occasionally, about 10 to 12 minutes. Drain pasta onto a large baking sheet. Spread to a single layer and let cool for 10 minutes.
Meanwhile, using a small knife cut the skin off the orange and grapefruit. Over a large bowl, cut out the segments of the citrus flesh and catch the juices. Add the onion, mint, basil, fennel seeds, salt, pepper, and cooled fregola pasta.
Add the reserved orange oil to the pasta. Toss all the ingredients together and serve.