Chicken thighs with mushrooms, leeks and bell peppers

This is a flavorful, saucy dish that goes great with warm, crusty bread to soak up the deliciousness!
Serves 3-4.
Ingredients:
3 Tbsp olive oil, divided
1/2 lb chicken thighs, about 3 thighs
1/2 tsp Italian seasoning mix, divided
1/4-1/2 tsp each salt & pepper, divided (or to taste)
1 leek, white part only, chopped
2 garlic cloves, chopped
1/2 red bell pepper, chopped
4 oz. mushrooms, chopped
1/2 cup stock or water
1 Tbsp tomato paste
1/2 tsp dijon mustard
1 Tbsp flour

Directions:
Preheat oven to 400F.  Rub chicken thighs in 1 Tbsp olive oil, 1/4 tsp each Italian seasoning, salt and pepper.  Roast uncovered in oven about 15 minutes, remove and let cool. Once cool enough to handle, cut into 1 inch cubes.  Meanwhile, saute leeks and pepper in remaining oil over medium heat. Add garlic and saute for 1 more minute, then add mushrooms and stir well for1 minute.  Add stock or water, cubed chicken, remaining Italian seasoning, tomato paste and mustard.  Bring to a gentle boil over med-high heat then reduce heat to med-low, cover and let simmer for about 20 minutes.  Remove cover and whisk in flour and stir well. Simmer to desired sauciness, about 5 minutes. Season with salt and pepper if needed.  Enjoy!