For the pilaf, melt butter in saucepot over medium heat, add pasta and toast to deep golden and fragrant. Stir in rice and stock, bring to boil then reduce heat to low. Cover and cook to tender, 18 minutes.
Preheat oven to 375ºF.
Heat olive oil in a soup pot, 2 turns of the pan, over medium-high heat. Add carrots, celery, onions, garlic, bay, herb bundle, salt and pepper, and cook partially covered, 5-7 minutes to soften. Add stock and bring to a boil, reduce heat and simmer. Add lemon juice to broth just before serving.