Mix together salt, mustard fennel, coriander, cinnamon and red pepper; crushing in the fennel seeds in a mortar & pestle or against the side of the bowl with a strong metal spoon.
Rinse and pat dry chicken breasts and evenly coat all sides with spice mixture.
Grill chicken and prepare sauce: mix olive oil, cilantro, lemon juice, garlic and a dash of salt in a small bowl. Drizzle oil mixture over chicken just prior to serving.
Olive oil mix may be made ahead of time and chilled -- the difference in temperatures between the oil and the chicken is rather pleasant.