Food: Terrine.

I’m not sure if it’s a professional hazard, or if I’m just a bit odd about numbers, but I love restaurant maths. I was never a good mathematical scholar when I was at school, but my basic arithmetic has always been solid and I’m not too shabby at percentages. Numbers, percentages and timing are all critical in kitchen work.

First, there are the operating costs to consider. How much does a dish cost to produce? What are the ingredients, what is the labour required, what is the expected waste? Where does it sit on a menu and, if inexpensive, can it cover for something else further down the list so there is balance? Then there are all the logistical maths of “service” – a finely choreographed dance between sections of the kitchen and the front-of-house staff who represent “the customer”. There’s a sixth sense that all good chefs learn, of how to pull different dishes from different sections of the brigade so that a table is served together, and everything is cooked and plated correctly. If you think about it too hard, it seems almost impossible, yet day after day, kitchen upon kitchen around the globe keeps sending food out without anyone giving it another thought.

And then there are the curious patterns that you find in the weights and measures of recipes. Of these, there are none I love more than charcuterie maths.

The charcuterie family encompasses things that are mainly pork, with the addition of game, poultry and offal. Terrines, pâtés, galantines, pâtés en croûte, rillettes, saucissons and hams all come into play. And with each of them there are mathematical certainties to ensure the end product is successful: the right amount of seasoning for the weight of meat, and the correct ratio of meat to fat.

In this instance I am looking at a basic terrine recipe. For this I follow a few rules.

Always buy meat that has been trimmed, or buy extra to allow for trimming off excess fat and sinew.

Meat needs to be minced for a good terrine. A food processor will not create an even result and can puree some of the meat, changing the texture of the finished product.

The ratio of meat to back fat should be 3:1 by weight. For the seasoning, use these proportions: salt, 2 per cent (or 20 grams per kilogram of meat–fat mixture); pepper, 4 grams per kilogram; quatre épices, 2 to 3 grams per kilogram.

Always have the ingredients very cold for mixing. For the best texture, it is great to use a stand mixer with the paddle attachment. This helps to knock all the air out and bind the ingredients.

Digital thermometers will help with the cooking process. An internal temperature of 70ºC will mean that all harmful bacteria have been killed.

Weighting your terrine after it is cooked is always recommended. I find the best weight is a house brick wrapped in aluminium foil. Again, this helps with the texture of the terrine.

This recipe serves as a guide only: you can tweak it as long as you follow the key rules. Trust the meat-to-fat ratio – use 225 grams of back fat, but with the meat you can change the combination to just pork, or pork and rabbit, et cetera. You can also add a handful of chopped herbs, some cooled sautéed spinach or onion, or a handful of pistachio nuts. Maybe you want to add a proportion of minced duck leg and lay the trimmed fillet down the centre. The zest of an orange would make a great flavour addition to that combination.

Terrine making is a very satisfying pursuit and not at all hard, especially if you follow the numbers.