Step 1

You can substitute 1½ teaspoons anchovy paste, if desired. If your fennel bulbs do not have fronds, you can substitute parsley or dill.

Step 2

Using highest sauté function, heat oil in Instant Pot until shimmering. Add fennel pieces, onion, and salt and cook until vegetables are softened, about 5 minutes. Stir in tomato paste, garlic, thyme, and anchovies and cook until fragrant, about 30 seconds. Stir in 5 cups water, scraping up any browned bits, then stir in tomatoes and carrots. Nestle chicken breasts and thighs in pot.

Step 3

Lock lid in place and close pressure release valve. Select high pressure cook function and cook for 20 minutes. Turn off Instant Pot and quick-release pressure. Carefully remove lid, allowing steam to escape away from you.

Step 4

Transfer chicken to cutting board, let cool slightly, then shred into bite-size pieces using 2 forks; discard skin and bones.

Step 5

Using wide, shallow spoon, skim excess fat from surface of soup. Stir chicken and any accumulated juices, olives, and remaining 2 cups water into soup and let sit until heated through, about 3 minutes. Stir in fennel fronds and orange zest, and season with salt and pepper to taste. Serve.