In a lg skillet, begin to saute onions in 2 Tbl. olive oil.
Slice the fennel bulb,placing the 2 "center cuts" in to the pan with the onions, slicing remaining fennel more thinly. Add to pan. Add the whole olives. Saute all til well caramelized, stirring frequently,about 10 min.
Meanwhile zest minniolas and set aside for garnish. Cut each in half and add juice of 3 halves squeezing juice over veggies. Using a grapefruit spoon, section out the remaining half. Lay sections on sauteed veggies. Push veggies to side of pan.
Add remaining 2 Tble. olive oil to cleared side. Place rockfish fillet skin side up, for 5 min. Gently flip fish and cook for 8 more minutes. The flesh side should be nicely caramelized from the veggies.
Divide veggies and rockfish fillet onto 2 plates placing fennel so it is backdrop for olives, orange segments.
Spoon 2 Tble. yogurt between fish and veggies and splash high quality olive oil on all. Sprinkle the minniola zest over all. Sea Salt to taste.