In a medium bowl, whisk together the garlic, shallot, salt, lemon zest and juice, and the orange zest and juice. Fold in the shaved fennel, fennel fronds and dill. Toss to coat. Add the orange segments, a few grindings of black pepper, coriander, olive oil and watercress. Toss gently and plate ingredients, spoon additional dressing over each portion.