Jody Adams' Chicken Stew

Ingredients

• 3 lb whole chicken
• 8 c chicken stock (or, 4 cans @ 13¾ oz each, low sodium chicken stock plus 1 c water)
• 3 c water
• 3 medium carrots, cut on an extreme diagonal
• 5 stalks celery, strings removed and cut on an extreme diagonal
• 3 medium leeks, white part only, cut on an extreme diagonal
• bouquet garni (1 bay leaf tied with a few stalks of parsley)
• pinch dried thyme
• 4 cloves garlic, smashed
• 1 T chopped fresh tarragon (or, 1 t dried tarragon)
• ½ c tiny star pasta, or any other ⅛" shape
• 1 T lemon juice, or to taste
• salt
• freshly-ground black pepper