cooking / soups

All-Day Vegan French Onion Soup (Denver Altitude)

Six hours of onions, cannellini beans for body instead of cream, and enough miso and Dijon to carry the savory weight the beef broth used to. Altitude tested at 5,280 feet.

serves 4-6 · about 6 hours, mostly unattended · easy but long

Ingredients

Onion Base

  • 3–4 lbs yellow onions, thinly sliced pole-to-pole
  • 1 tbsp olive oil
  • ¾ tsp kosher salt
  • 1 tbsp tomato paste
  • ¾ cup dry white wine (split use)

Broth + Body

  • 6–8 cups strong homemade vegetable broth
  • 2 cans cannellini beans, drained and rinsed
  • 2–3 tsp soy sauce (adjust to taste)
  • 1 tsp Dijon mustard
  • 1½–2 tsp white miso
  • 1 tbsp nutritional yeast
  • ½–1 tsp aged balsamic vinegar (to taste)

Spice Structure

  • ½ tsp sumac (used lightly, mostly for garnish)
  • ⅛ tsp white pepper
  • Generous freshly cracked black pepper

Toast

  • Baguette slices
  • Nutritional yeast (for topping)
  • Optional tiny dusting sumac per bowl

Method

1. Slow Onion Collapse (2½–3 hours)

In a heavy Dutch oven over medium-low heat:

  1. Add olive oil.
  2. Add onions + salt.
  3. Cover for 20 minutes to sweat.
  4. Uncover and cook low for 2½–3 hours, stirring every 8–15 minutes.

At altitude:

  • Keep heat slightly lower than instinct.
  • Add small splashes of water if sticking aggressively.

Cook until onions are deep chestnut / mahogany, jam-like, and reduced ~75%.

2. Concentration Cycles

Increase heat slightly.

  • Let fond develop.
  • Deglaze with a splash of white wine + a few drops soy.
  • Reduce fully.

Repeat 2–3 times.

Add tomato paste during the final cycle and cook until slightly darkened.

(Optional: stir in a small pinch of sumac and briefly bloom before final deglaze.)

3. Broth + Bean Integration (45–60 minutes)

Add:

  • Vegetable broth
  • Cannellini beans

Bring to a gentle simmer. Cook uncovered or partially covered depending on desired reduction.

After ~30 minutes:

  • Remove 3–4 cups (beans + broth + onions).
  • Blend completely smooth.
  • Return to pot.

Simmer another 10–15 minutes until broth lightly coats a spoon.

4. Final Architecture (Gentle Heat Only)

Lower heat.

Add in order:

  1. Dijon (whisked into hot broth first)
  2. White pepper
  3. White miso (whisked into hot broth first)
  4. Nutritional yeast (whisked into hot broth first)
  5. Soy sauce (adjust gradually)

Simmer gently 5–7 minutes.

Add balsamic in ¼ tsp increments until the soup feels rounded but not acidic.

Finish with generous freshly cracked black pepper.

Rest 3–5 minutes before serving.

Toast

Toast baguette at 350°F until crisp.

While warm:

  • Sprinkle nutritional yeast.
  • Optional light brush olive oil.

Float on soup.

Garnish individual bowls with:

  • Tiny dusting of sumac
  • Fresh cracked black pepper

Texture Target

Broth should:

  • Lightly coat a spoon
  • Feel velvety from blended beans
  • Not read as stew
  • Not read as thin broth

Flavor Notes

Deep caramelized sweetness
Savory fermented backbone
Rounded mid-palate
Warm pepper structure
Bright lift from light sumac

Elegant, structured, plant-forward French onion.