Chicken Stew with Vegetables and Grains

This is a recipe I wanted to try out after making a similar ready-made mix. I changed it up a little bit, adding vegetables and changing the cooking process. I imagine, it is also possible to make a vegetarian version of this stew.

2 cups mix of beans, rice and lentils
salt
garlic
rosemary *other spices
1 big onion, chopped
4 carrots, chopped
1 celery, chopped
1 - 2 pound chicken breast
10 cups vegetable or chicken stock

Wash the grains, set aside.
Heat up oil and add onions in a big pot. When onions are cooked add spices and chicken and cook for about 5 minutes. Add vegetables and cook for another 5 minutes. Add stock and grains and cook until grains are done.