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Lunch recipe · from the recipe book

Silky Onion Thyme Soubise with Mozzarella

A sweet, slow-cooked onion sauce puréed until velvety, with gentle thyme and a mellow, stretchy mozzarella finish that browns well on gratins.

Silky Onion Thyme Soubise with Mozzarella

Ingredients

  • 2½ medium300 gYellow onionthinly sliced
  • 1½ tbsp20 gUnsalted butter
  • ¼ cup60 gWater
  • 2½ tbsp18 gAll-purpose flour
  • 1⅔ cups (390 ml)400 gWhole milk
  • 2 tsp2 gDried thyme
  • 2 oz60 gPart-skim mozzarellashredded
  • ⅛ tsp1 gSalt
  • ½ tsp1 gBlack pepper

Steps

  1. Before you start, slice the onion thinly and shred the mozzarella; measure the milk so it is ready.
  2. Melt the butter in a medium pot over medium-low heat. Add the onion and the water, cover, and cook gently for 15 to 20 minutes, stirring now and then, until the onion is very soft and pale gold but not browned.
  3. Uncover, sprinkle the flour over the onion, and stir for 2 minutes to cook out the raw flour taste.
  4. Slowly pour in the milk, whisking constantly, then add the thyme. Bring to a gentle simmer and cook, stirring, for 5 minutes until thickened.
  5. Take the pot off the heat and purée the sauce with an immersion blender until silky.
  6. Stir in the mozzarella until melted and smooth, then season with the salt and black pepper.
  7. Spoon the sauce over vegetables or potatoes in a gratin dish and bake until bubbling and browned on top.

Contains: Milk, Gluten.

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Saved in the Every Helping recipe book on October 24, 2026.

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