First poach the chicken breasts: in a medium-sized soup pot, lay the chicken breasts beside each other, pour in just enough cold water to cover the chicken breasts, and add bay leaves.
Turn the heat to high, bring the cold water to boil then reduce heat to simmer. Use a digital thermometer to check the internal temperature of the chicken; when it reaches 70°C (160°F) in the thickest part, remove the breasts and set aside.
Use a strainer to remove impurities and scum from the poached chicken water, which is now your stock, add a litre of water and salt, and boil for 5 minutes.
While the stock is boiling, in a separate pan over medium-high, heat the olive oil, fry the purple shallots until soft, add the garlic slices and fry until fragrant (don’t let the garlic brown), then transfer to the stock.
Add the chopped potatoes, carrots and celery stalks to the stock and continue to cook until the potatoes are tender.
Use two forks or clean hands to pull the chicken breasts apart into large pieces and add them to the soup, along with the lentils, stir, and cook for five minutes.
Taste and adjust the seasoning if needed, add the fresh dill, a teaspoon of pickled shallots and pickle juice, stir, and serve immediately with crusty bread.