Remove the dill fronds from the stems. Rough chop ½ cup of the fronds and add to a bowl with the mustard, olive oil, salt, pepper, and the zest of 1 lemon. Mix well into a paste.
Coat the top of the salmon with the paste and let sit in the refrigerator for 30 minutes.
Preheat your Spark to 500°F and brush the grates with oil.
Cook the salmon, skin side down, 6-8 minutes or until the skin easily releases from the grates and the flesh becomes opaque. The salmon will be cooked to medium following these directions; if you prefer the salmon more or less done, alter the cooking time accordingly.
Serve with lemon wedges and garnish with extra dill fronds.