1. Heat 2 tablespoons (30 milliliters) of the olive oil in a large pot or Dutch oven over medium heat until shimmering. Add the onion and cook, stirring and adding small amounts of the stock to help steam the onion, for 5 minutes or until the onion is soft and translucent. Add the garlic and cook, stirring, for 1 minute or until fragrant.
2. Stir in the remaining stock, the potatoes, dill, 1 teaspoon (6 grams) salt, and 1/2 teaspoon pepper, and simmer over medium-low heat until just tender.
3. Heat the remaining 1 tablespoon (15 milliliters) olive oil in a medium skillet over medium heat until shimmering. Add the chard and kale and cook, stirring, for about 3 minutes or until wilted. Stir them into the pot.
4. Add the chicken, if using, and heat through, then season the soup with salt and pepper to taste and add the lemon juice. Serve.