French Onion Soup Yorkshire Puddings with Gravy

Preheat oven to 220°C (425°F). Grease a mini muffin tin with vegetable oil and place it in the oven while it preheats.

In a bowl, whisk together the flour and salt. In a separate bowl, whisk the eggs and milk. Gradually whisk the wet ingredients into the dry ingredients until you have a smooth batter. Let the batter rest for at least 15 minutes (or up to an hour) at room temperature.

While the batter rests, prepare the caramelized onions: Melt butter in a large skillet over medium heat. Add the sliced onions and cook, stirring occasionally, for 20-30 minutes, or until deeply golden brown and caramelized. Add the brown sugar (if using) and balsamic vinegar (if using) during the last 5 minutes of cooking. Season with salt and pepper to taste. Remove from heat and set aside.

Make the gravy: in a saucepan, heat the vegetable broth. In a small bowl, whisk together the cornstarch and cold water. Slowly pour the cornstarch slurry into the simmering broth, whisking constantly to avoid lumps. Continue to simmer until the gravy thickens to your desired consistency. Season with soy sauce (if using), salt, and pepper to taste. Keep warm.

Carefully remove the hot muffin tin from the oven. Quickly pour the Yorkshire pudding batter into each cup, filling them about two-thirds full.

Bake for 18-22 minutes, or until the Yorkshire puddings are puffed up and golden brown. Do not open the oven door during baking to prevent them from deflating.

Remove the Yorkshire puddings from the oven and let them cool slightly in the tin before transferring them to a wire rack.

To assemble, fill each Yorkshire pudding with a spoonful of caramelized onions, top with a generous spoonful of gravy, and sprinkle with grated Gruyere cheese.

Garnish with fresh thyme leaves (optional) and serve immediately.