The chicken in the light and refreshing preparation is poached to allow the various citrus flavors to shine through.
Remove skin and trip wing bone from chicken breasts; reserve. In a stockpot, combine stock, wine, lemon juice, lemon grass, bay leaf, and peppercorns. Bring to a light simmer. Season chicken with salt and pepper and place in the simmering stock. Return to a simmer and poach until cooked through, about 10 minutes. Removed chicken, place on a platter, and tent with foil to keep warm. Reserve poaching liquid at a slow simmer.
In a 2-quart saucepan, heat olive oil over medium heat. Add shallots and cook until softened. Add orzo, stirring to coat with the oil, and then add 2 cups reserved poaching liquid, orange juice, and half the orange zest. Bring to a simmer and cook orzo, stirring occasionally, until liquid is absorbed, about 12 minutes. Keep warm.
Meanwhile, in a small saucepan, heat butter over medium heat. Add sugar and cook until golden brown. Add half of the orange segments, stir once, and remove pan from heat to allow segments to soften in syrup.
Add water to remaining simmering stock to equal 2 cups; season with salt. Add zucchini and squash and cook, covered, until tender. Remove with a slotted spoon to a warm bowl and ladle a little poaching liquid over them to keep them warm.
To serve, return chicken breasts to simmering poaching liquid just long enough to reheat. Stir parsley, chopped basil, and the remaining orange segments into the orzo and divide it among the plates. Place a breast on each pile of orzo. With a slotted spoon, transfer squash slices to plates. Garnish plates with caramelized orange segments, remaining reserved orange peel, and whole thyme leaves. Serve immediately.