Dice the onion, carrot, and celery into small, even pieces (about 1/4 inch) so they cook at the same rate. Mince the garlic. Zest both lemons before juicing - you'll need about 1/3 cup juice total.

Heat olive oil in a large Dutch oven over medium heat. Add onion, carrot, and celery with a pinch of salt. Cook for 6-8 minutes, stirring occasionally, until vegetables soften and the onion turns translucent but not brown. Add garlic and oregano; cook 1 minute more until fragrant.

Pour in the vegetable broth and add chickpeas, orzo, bay leaf, and 1/2 teaspoon salt. Bring to a boil, then reduce heat to maintain a gentle simmer. Cook uncovered for 10-12 minutes, stirring occasionally, until orzo is tender but still has a slight bite. The soup will thicken as the orzo releases starch.

Remove from heat. Discard the bay leaf. Stir in lemon zest, lemon juice, fresh dill, grated Parmesan, and black pepper. Taste and adjust salt - the Parmesan adds saltiness, so you may need less than you think. The soup should taste bright and lively from the lemon.

Let the soup rest for 5 minutes off the heat. This allows the orzo to absorb more flavor and the soup to thicken slightly. Ladle into bowls and top with extra dill, Parmesan, and a drizzle of olive oil if desired. Serve with crusty bread.