Creamy chicken and rice soup - chinese grandma

Ingredients

• 1 cup yellow onion, diced
• 1 cup celery, diced
• 1 cup carrots, diced
• 2-3 tablespoons olive oil
• 3/4 teaspoon dried thyme
• 2 cups diced chicken breast (raw or cooked)
• 3/4-1 cup white or brown rice (3/4 cup makes a looser soup)
• 8 cups chicken stock or broth
• 4-5 drops Worcestershire sauce
• 6 drops Tabasco sauce (or to taste)
• A shake of cayenne pepper (or more to taste)
• Salt and pepper, to taste
• 3 tablespoons butter
• 3 tablespoons flour
• 2 cups milk