Step 1

Place the chicken, water, quartered onion, peppercorns, and salt in a 5-quart or larger Dutch oven. Cover and bring to a boil over high heat, then reduce heat to maintain a simmer until the chicken is cooked through, about 45 minutes to 1 hour. If any white foam forms, use a slotted spoon to skim off and discard.

Step 2

Transfer the chicken to a cutting board. Strain the stock through a fine-mesh strainer set over a large heatproof bowl and discard the solids. Skim off fat rendered from the chicken thighs with a spoon . Reserve 2 cups of the stock in a measuring cup. Return the remaining stock to the Dutch oven and place over low heat to keep warm.

Step 3

When the chicken is cool enough to handle, remove the meat from the bone and shred into bite-sized pieces with your hands; set aside. Discard the skin and bones.

Step 4

Bring the stock to a boil over medium-high heat. Add the orzo and cook until al dente, 7 to 9 minutes. Stir in the reserved shredded chicken. Reduce the heat to low.

Step 5

Place the eggs in a medium bowl and whisk until lightened in color and frothy, about 2 minutes. Continue to whisk while gradually adding the lemon juice. While constantly whisking, temper in the eggs by slowly drizzling the reserved 2 cups of warm stock into the egg-lemon mixture. This warms the eggs just enough so that they do not curdle when added to the hot soup.

Step 6

Add the avgolemono mix back into the pot with the chicken and orzo and stir to combine. Cook until the soup thickens slightly, 3 to 5 minutes, but do not let it come to a boil.

Step 7

Pour the soup into serving bowls and serve with lemon slices, fresh chopped dill, and lots of freshly ground black pepper.