How to convert a recipe to the pressure cooker

Julia Child’s French Onion Soup – pressurecookerized

French Onion Soup Pressure Cooker Recipe
Pressure cookbooks, websites and even manuals say that you only need to cut down the cooking time to convert a recipe to the pressure cooker – but there is so much more to consider!In Julia Child’s memory and spirit, I take her soup – a classic in many American households – to teach you two of the many things to watch out for when converting a recipe to the pressure cooker.

The whole idea came together while watching Julia Child’s “The French Chef” cooking show , I spotted a pressure cooker in the program. She did not specifically mention it other than saying the meat stock in it was simmered for 5 to 6 hours (uh..huh! ; )

It was during the Soupe a L’Oignon (Onion Soup) episode that  I realized that there are couple of things that could go wrong if one tried to make this recipe, as demonstrated and written, in the pressure cooker by only reducing the cooking time.

Julia’s recipe is the perfect instrument to illustrate two, of many, things to keep in mind when converting a traditional recipe to your pressure cooker:

Thickening – In the traditional method, Julia Child throws in some flour and butter right after caramelizing the onions to give the soup a nice body. Unfortunately, thickening with flour,  starch, puree or flakes before pressure cooking will “solidify” most of the liquid that needs to boil and make vapor to reach pressure. This could either result in the pressure cooker not reaching pressure at all or, if it does, spurting thick liquid instead of vapor when pressure is released.

HOW TO DO IT: Add the thickeners after pressure cooking. In this recipe, I cook the butter and flour in a little pan separately.  When the soup is finished pressure cooking, I whisk this mixture into the pressure cooker and simmer everything together.

Flavoring with Wine– In the traditional method, Julia Child pours in 1 cup of wine to boil, simmer and eventually evaporate it’s liquid in the soup. Unfortunately, wine will not evaporate while boiling under pressure. The wine will remain as fully flavored and tangy as  when it was first poured in the soup dominating the flavor and leaving an unpleasant effect..

HOW TO DO IT: Reduce the quantity of wine and fully evaporate it before pressure cooking.  In this recipe, I use the wine to de-glaze the onions and evaporate it almost completely before adding broth. The wine will leave its essence without eviscerating the caramelized onion flavor base.

Finally,  in pressure cookerizing Julia’s recipe, the softening and caramelizing steps should still be done without pressure, but all of the simmering and boiling can be done under pressure.

The more thinly you can slice the onions the faster each step not under pressure will go. A good mandolin is indispensable for this recipe – giving you paper-thin slices and cutting the time to caramelization in half from the original recipe.

To save even more time, I slice the onions directly into the pre-heated pressure cooker into the simmering butter and oil.

Pressure Cooker Accessories Pr. Cook Time Pr. Level Open
5 L or larger  none 5 min.  High (2)  Normal

5.0 from 1 reviews
Pressure Cooker French Onion Soup
Recipe type: pressure cooker recipe
Cuisine: French
Prep time: 
Cook time: 
Total time: 
  • 1 Tbsp. Butter
  • 1 Tbsp. Oil
  • 1.5 lbs or 5 cups, or 5 large Yellow Onions, thinly sliced
  • ¼ Onion, wedge (to grate later)
  • 1 tsp. salt
  • ¼ tsp. sugar (or two pinches)
  • ½ cup of dry white wine
  • 6 cups or 1.5L Meat Stock
  • 3Tbsp. Cognac
Blond Roux:
  • 4 Tbsp. or 60gr Butter
  • ¼ cup or 60gr Flour
To Garnish:
  • 12-24 French bread slices – about 1” thick, painted with olive oil and toasted
  • 1 cup of grated Gruyère or Swiss cheese
  • ½ cup of "chipped" Gruyère or Swiss cheese -thinly sliced pieces using a potato peeler
  1. In the pre-heated pressure cooker, on medium-low heat, add the butter and oil.
  2. Soften the onions, stirring occasionally in the pressure cooker covered with a normal lid or pressure cooker lid set at NO PRESSURE until the onions become translucent (about 15 minutes). Then, turn down the heat to low, without a lid, add the salt and sugar and stir frequently until the onions have turned a uniform brown (about 10 to 15 minutes).
  3. In a small, separate pan, make the Blonde Roux by adding equal amounts of butter and flour and stir them on medium heat until all of the butter has melted and the flour begins to foam (this means it’s cooked), continue stirring occasionally and watching carefully until it turns a nice tan color. Turn off the heat and set aside.
  4. Back to the pressure cooker, de-glaze the caramelized onions with the white wine and let it evaporate completely. Then, add the meat stock.
  5. Close and lock the pressure cooker. Turn the heat to high until the pressure cooker has reached HIGH pressure . Turn down the heat and begin counting 5 minutes pressure cooking time. When time is up, turn off the heat and open the pressure cooker using the Normal method – press the button, twist the knob or lift the valve.
  6. Taste and adjust for salt and pepper seasoning then put a soup ladel’s worth of soup (about ½ cup) into the little pan with the roux - flour and butter mixture - and whisk together. Pour the mixture into the pressure cooker, on medium heat without the pressure cooking lid, and simmer together for a few minutes. Turn off the heat, and add Cognac and finely grated fresh onion wedge.
  7. Pour soup in individual soup bowls or serving tureen.
  8. Sprinkle the soup with cheese chips, then covering with toasted French Bread slices, then covering those with generous amounts of grated cheese. Slip under the broiler until the top is cooked and golden (2 to 3 minutes).
  9. This recipe can be halved or doubled without changes - providing the liquid does not exceed your pressure cooker's maximum capacity.

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Pressure Cooker French Onion Soup - Julia Child