Slice the top off each orange and carefully slice away the skin by cutting from the top of the orange to the bottom, following the curvature of the fruit, making a half turn each time. Clean away any extra pith.
Cut the fennel bulb into half and then half again. Remove the heart and slice each quarter very thinly.
Mix all ingredients except feta, mint, fennel pollen and fennel fronds in a medium size mixing bowl.
Taste and adjust seasoning. Transfer to serving platter or bowl.
Garnish with crumbled feta, torn mint leaves, fennel fronds, fennel pollen and olive oil.