1. Heat olive oil in a large pot over medium heat until shimmering. Add diced chicken breast and cook without stirring for 2 minutes before turning — wait for genuine golden color on at least one side.
2. Add diced onion and minced garlic. Cook until onion is translucent and garlic is fragrant, about 3-4 minutes, scraping up any golden bits from the chicken.
3. Pour in chicken broth and bring to a simmer. Add sliced carrot and chopped celery.
4. Cook for about 10 minutes until vegetables are genuinely tender and broth is fragrant and developed.
5. Stir in chopped watercress and set a timer for exactly 5 minutes — cook until just wilted and tender but still vibrant green.
6. Season carefully with salt and pepper. Taste and adjust before serving immediately while watercress is still bright.

Nutrition Information (Per Serving):

• Calories: 155
• Carbohydrates: 8g
• Protein: 20g
• Fat: 4g
• Fiber: 2g
• Sodium: 720mg
• Key vitamins/minerals: Vitamin K (85% DV from watercress), Vitamin C (35% DV), Vitamin A (40% DV), Calcium (12% DV)
• Note: Watercress is among the most nutrient-dense leafy greens available — exceptional vitamin K and vitamin C content in a soup that happens to also be genuinely delicious and satisfying.

Notes:

• Time the watercress addition carefully — 5 minutes preserves its color and peppery flavor; longer turns it yellow and slightly bitter
• Store watercress separately from the finished soup if making ahead — add fresh when reheating
• Season confidently at the end — light broths need bold final seasoning to taste complete

Storage Tips:

• Store soup base without watercress for up to 3 days refrigerated — add fresh watercress when reheating
• Freeze soup base without watercress for up to 3 months — add fresh watercress after reheating
• Reheat gently on the stovetop over medium heat — avoid boiling, which toughens the chicken

Serving Suggestions:

• Serve with crusty bread for a complete light meal
• Add a soft-boiled egg halved into each bowl for extra protein and richness
• Pair with a simple side salad for a balanced, complete weeknight dinner
• A drizzle of good olive oil over each bowl adds richness and a beautiful finish

Mix It Up (Recipe Variations):

• Ginger Addition: Add a teaspoon of freshly grated ginger with the garlic for a warming, slightly Asian-inspired depth that pairs beautifully with watercress’s peppery bite
• White Bean Version: Stir a cup of drained white beans into the broth for extra heartiness and plant-based protein that turns this into a genuinely substantial meal
• Mixed Greens Swap: Replace half the watercress with baby spinach for a milder, more approachable version that works beautifully for anyone new to watercress’s distinctive flavor

What Makes This Recipe Special: Watercress brings something to chicken soup that no other commonly used green can replicate — a gentle peppery quality that makes the broth taste more complex and interesting without adding any additional aromatics or seasoning. Adding it only in the final 5 minutes of cooking is the technique decision that preserves this character rather than cooking it away, which is what separates this chicken and watercress soup from a basic chicken vegetable bowl and makes it worth making specifically rather than with whatever green happens to be in the fridge.