start by listing out all of the ingredients in the recipe. Then figure out how much of each ingredient you're going to use, and what unit you're going to measure each quantity by.

Now's the annoying part. Often you need to use a different unit measurement than you bought it by. You may need 5 oz of flour which you purchased by the 50 lb bag, a 1 lb container of spice and need to use 1 tsp, or a case of squash by the each and you need to have 14 oz, fine dice. So you're going to need to convert from your purchase unit to your recipe unit, and take into account the average amount of trim you'll incur along the way.

This might mean that you count how many olives you have in 1 lb, and use that to calculate how many are in 1 21lb bucket. Or that you grab a tablespoon and measure how much 5 fl oz weighs. Or that you trim down a couple cuts of steak, taking your starting and end weight and calculate your yield.

E.g. 113 olives per lb, in a 21lb tub that costs $34

(113 olives x 21 lbs)/($34 / 1lb) = 70 olives per $1

($34 / 1lb)/(113 olives x 21 lbs) = $.014 per olive

E.g. how many teaspoons are in a 1 kg container of sea salt? using a ladle, weigh out a decent quantity. The more you use, the more accurate your average will be. If you simply weigh 1 tsp, it will vary considerably.

let's say 8 fl oz = 220g

8 fl oz / .22 kg = 36.4 fl oz/kg

there are 6 teaspoons in a fl oz, so 6 teaspoons x 36.4 fl oz/kg = 218 tsps/kg

E.g. You purchase hanger steak at $5.70/lb and need to trim it down. How much does the trimmed meat cost? There's a large amount of variation in any natural product. Some steaks will have more connective tissue, more fatty surface deposits, more undesirable muscle. So, say you start with 35.2 lbs, and when you're done, you have 20 lbs 5.3 oz.

5.3 oz/(16 oz/1 lb) = .33

so 20.33 lbs

20.33 lbs/35.2 lbs = 57.8% yield per lb

$5.70 per lb / .578 yield per lb = $9.86 per trimmed lb

So you've created a list of all of your ingredients, measured those ingredients, and priced them according to their cost per recipe unit. Now total up the cost per each quantity of ingredients. This is how much it costs per dish. Your food cost % will be how much each dish costs divided by how much you sell it for.

If you want to target a specific %, then you can divide your cost per dish by the percent (remember to move the decimal two places to the left (35% = .35):

$3.2 per dish / 28 % food cost goal = 3.2/.28 = $11.4 menu price.

Now a food costed recipe isn't enough to make sure your food costs are in line. You need to be on top of your cooks and making sure that they are actually following the recipe, that they aren't introducing unnecessary waste while they're prepping, that they're logging wasted product, that your line cooks have few errors, that your serving staff actually take the food to the right table/get the order right in the first place, etc.

Additionally, some dishes are going to sell really well, and some will sell poorly. While it is ideal for each dish to be priced at the target food cost, what really matters is your overall food cost %. If you have several dishes which sell great and have a low fc% and a dish that has a high fc% but sells ok, they can balance each other out, and you can offer higher quality or cost ingredients at a subsidized price to your customers.