Avocado and Grapefruit Salad

I never miss an episode of the Barefoot Contessa, thanks in large part to our new DVR. The show features new recipes from "How Easy Is That?" and some popular episodes are also re-broadcast. 
On a recent show Ina went to a local farm to select the freshest, most-seasonal ingredients for a three-course meal she was preparing for some friends. Fresh and colorful corn, ripe and flavorful tomatoes, as well as the most gorgeous basil and herbs.  
Of course this made me long for the days when we got fresh, local and seasonal vegetables from our CSA (weep). But alas, our CSA share ended three months ago and we have a few more months to go before delivery starts again...   
I've been eating a ton of apples, squashes, potatoes, and legumes, but what is really 'in season' right now, and bursting with flavor, is citrus. (It's very seasonal, but not very local-- so you can be the judge of how your 'environmental footprint' is doing and make your purchases accordingly...)
I've been having a severe craving for all things citrus recently: blood oranges (see this post), limes, lemons, oranges and ruby red grapefruits.  I thought I was going to go out of my mind the other day if I didn't get my hands on a Steve's Key Lime Pie.  You know you have problems when you think of going out in a snow storm to get that perfect pie-- graham cracker crust with the most delicious key lime filing. Topped with whipped cream? Yes please! But that's a story for another time...
Anyway, this salad makes the most of the season's best fruit. I had it for the first time at my husband's aunt's home and was waiting to make it again-- and then I saw the most perfect ruby red grapefruits and I knew the time had come. Enjoy!
Avocado and Grapefruit Salad (Courtesy of Ina Garten)
Yields 4-6
1 tablespoon Dijon mustard
1/4 cup freshly squeezed lemon juice
1 1/2 teaspoons kosher salt
3/4 teaspoon freshly ground black pepper
1/2 cup good olive oil
4 ripe Hass avocados
2 large red grapefruits

Place the mustard, lemon juice, salt, and pepper in a small bowl. Slowly whisk in the olive oil until the vinaigrette is emulsified.
Before serving, cut the avocados in 1/2, remove the pit, and carefully peel off the skin. Cut each half into 4 thick slices. Toss the avocado slices in the vinaigrette to prevent them from turning brown. Use a large, sharp knife to slice the peel off the grapefruits (be sure to remove all the white pith), then cut between the membranes to release the grapefruit segments.
Arrange the avocado slices around the edge of a large platter. Arrange the grapefruit segments in the center. Spoon the vinaigrette on top, sprinkle with salt and pepper, and serve.