Combine shallots with white wine vinegar, lemon and orange juices and pinch of salt. Macerate 15 minutes. Whisk in 3/4 cup olive oil, and stir in chervil and zest. Adjust seasonings.
04Cut avocados in half lengthwise, and remove pits. Leaving skin intact, cut avocados lengthwise into 1/4-inch-thick slices. Scoop out slices with a large spoon, and arrange on a platter or individual dishes. Season with salt and pepper. Arrange beets on top, and drizzle with shallot mixture. Garnish with chervil sprigs.