In a large pot, heat the olive oil until shimmering. Add the leek and poblano and cook over moderate heat, stirring, until softened, about 8 minutes. Add the zucchini and garlic, season with salt and pepper and cook, stirring occasionally, until crisp-tender, 5 to 6 minutes. Add the chicken broth and Parmesan rind and bring to a boil. Simmer over moderate heat until the zucchini is very tender and no longer bright green, about 15 minutes. Discard the Parmesan rind and add the chopped cilantro.