Heat your oven on grill - hot! Place your nectarines cut side down for 2 minutes and check every minute until you're ready to turn them over to get the nice grill marks! Set aside.
Whisk the mustard, sugar and vinegar with a little salt and pepper.
Toast the slivered almonds in a small fry pan over medium-low heat until just turning golden brown.
In a large bowl, toss the salad greens with just enough of the dressing to lightly coat.
Divide the salad among 4 plates, sprinkle the almonds and place two halves of nectarine on each serving. Drizzle the nectarines with a little more dressing. With a fork, cut the feta into small chunks and divide and place on top of each salad.
This recipe really looks fabulous and yet it's super easy - so long as you carefully watch the grilling!