Using a mandoline, slice the fennel into thin shavings.
Cut the bottom and top off of the grapefruit. Using a knife, cut the peel off of the sides, following the curve of the grapefruit and being careful only to cut away the peel and bitter pith. Hold the fruit in 1 hand over a bowl and cut the flesh of the grapefruit away from the membrane to release a wedge. Repeat until all segments are released.
In a large saute pan over medium heat coat with extra-virgin olive oil and add the fennel. Season with salt and saute for 1 to 2 minutes or until the fennel is warm and coated with the oil. Remove from heat. Toss in the grapefruit segments, olive slivers and juice and sprinkle with the fennel fronds. Serve immediately.
Recipe courtesy of Anne Burrell