Im making some stock's today. About to roast some mirepoix, beef rib bones and a chicken carcass and bones. Than I'll split the roasted mirepoix between 2 pots, put the roasted chicken parts in one pot and the roasted beef bones in another pot. Fill both with water, add aromatics, peppercorns, bay leaves. Let come to a boil than reduce heat so they're at a cool simmer. Reduce 1/3 down or 4-6 hours. Strain out veggies and bones, store in air tight bottle in fridge. Use the stock in dishes to replace water like rice.