First, segment your oranges and remove the membranes. Using a sharp knife, cut off the top and bottom of the orange. Then cut down the sides to remove the peel and the white bitter pith. Using a pairing knife, separate the orange segments from the membranes. Do all of this over a bowl so you can catch the fresh juice that will inevitably spill out from the orange. There’s also quite a bit of juice left in the membranes, so squeeze it in your palm to release the rest.
Mix all of the dressing ingredients, except for the olive oil. In a constant, slow stream, begin to whisk in the oil until well incorporated.
Combine the arugula, orange slices, fennel, and slivered almonds in a bowl. Pour about 1/4 cup of the dressing over the salad and sprinkle a pinch of salt and ground pepper over the top then toss to mix.