Japanese Curry from Scratch

Name: Japanese Curry from Scratch
Ingredients: 550 grams chicken thighs - boneless skinless; 1 teaspoon salt; 1/4 teaspoon black pepper; 1 tablespoon oil; 14 grams garlic grated (~2 large cloves); 14 grams ginger grated (~1/2-inch piece); 500 grams onion sliced thin (2 large onions); 2 1/2 tablespoons curry powder Japanese brand such as S&B; 3 cups chicken stock; 300 grams carrots cut into chunks (~ 2 carrots); 1 small apple peeled cored and grated; 2 tablespoons chunou sauce; 1 tablespoon tomato paste; 1 teaspoon cocoa powder; 1 bay leaf; 350 grams potatoes cut into large chunks (~2 medium potatoes); 1/2 cup green peas; 1 tablespoon butter; 1 tablespoon flour