Step 1

Season the chicken with the salt and the pepper.

Step 2

In a large skillet over medium-high heat, heat the olive oil.

Step 3

Add the chicken and cook until golden, about 5 minutes.

Step 4

Reduce the heat to medium.

Step 5

Add the onion and cook until translucent and soft, about 3 minutes.

Step 6

Add the mushrooms and cook, while stirring occasionally, until softened, about 4-5 minutes.

Step 7

Stir in the garlic and sauté until fragrant, about 30 seconds.

Step 8

Pour in the chicken broth, the wine, and the sherry and bring the mixture to a boil.

Step 9

Stir in the Greek yogurt, 1/4 cup of the dill, and the Dijon mustard until well-incorporated.

Step 10

Add the butter and stir until melted.

Step 11

Place the flour in a small bowl.

Step 12

Add a ladle of the hot broth mixture to the flour and whisk the mixture until smooth and no lumps remain.

Step 13

Pour the flour-broth mixture back into the skillet and stir until well-incorporated.

Step 14

Reduce the heat to low and simmer until the sauce starts to thicken, about 3-4 minutes.

Step 15

Taste for seasoning and add more of the extra dill as needed.

Step 16

Serve.