In a large pot, heat the olive oil over medium-high heat. Season the chicken with salt and pepper. Add to the pot and cook, turning occasionally, until golden, 6 to 8 minutes; transfer to a plate. Let cool slightly before shredding.
Add the chicken broth and 2 cups water to the same pot and bring to a simmer. Add the tortellini and cook according to package directions. Remove from the heat and stir in the shredded chicken, the escarole, peas, scallions, lemon peel, lemon juice and mint. Season with salt and pepper.