Cooking with ferments brings a tremendous amount of flavour to whatever you’re making, and it’s a great way to showcase how an ingredient evolves through the application of heat. The idea of combining a Korean preservation method with a French technique is exactly what I love about creativity in the kitchen. This mirepoix kimchi is not just a fun ferment to dot on savoury oatmeal or eat alongside cheese, but it also acts as the backbone for a plant-based, umami-filled chilli.

Mirepoix kimchi (pictured top)

This versatile, umami-rich paste is a twist on the classic mirepoix and can be used to add a hit of flavour to everything from soups to marinades, or even enjoyed as is.

Prep 10 min Ferment 2** weeks+** Makes 500ml jar

150g carrot 150g white onion 150g celery 13½g salt (or 3% of the total weight of the first three ingredients) **½ **tbsp red miso, or fish sauce **½ **tbsp sugar 15g gochugaru chilli flakes

Roughly chop the vegetables (there is no need to peel the carrots if they have been rinsed), then put them in a food processor. Add the remaining ingredients and blitz to a rough paste.

Decant the paste into a sterilised 500ml jar and pack it down to ensure there are no air pockets; there may not be much brine, so to minimise oxygen exposure, lay a piece of greaseproof paper on top of the mirepoix to act as a barrier.

Seal the jar and leave to ferment at room temperature and out of direct sunlight for at least two weeks. At the two-week mark, start tasting the kimchi and, once you’re happy with the flavour and tang, store the jar in the fridge.

Vegetarian umami chilli

Kenji Morimoto’s vegetarian umami chilli.

This plant-based chilli is a powerhouse of flavour, thanks to the mirepoix kimchi and miso offering layers of heat and umami. It can easily be bulked out with your favourite chilli toppings and accompaniments, such as a jacket potato or rice.

Prep 20 min Cook 3 hr+ Serves 4-6**, with leftovers**

1 tbsp olive oil 250g mirepoix kimchi (see recipe above) 50g tomato paste 2** ****400g ****tins chopped tomatoes 2 **400g tins red or kidney beans, drained 100g dried red lentils, rinsed 400ml water 2 mild chillies, stalks, pith and seeds discarded, flesh chopped **3 **tbsp red miso 25g dark chocolate **1 ****tsp smoked paprika 2 ****tsp chipotle chilli flakes 2 ****tsp oregano 2 tsp ground cumin 1 **tbsp ground coriander

To garnish **Chopped fresh coriander Lime wedges Soured cream, or creme fraiche or greek yoghurt Grated **cheddar

Put the oil in a pan on a medium-low heat, then add the mirepoix kimchi and the tomato paste, and cook, stirring, for three to five minutes, until the residual liquid from the kimchi has evaporated and the paste turns dark and aromatic.

Transfer the kimchi mix to a slow cooker, add all the other ingredients other than the garnishes, and cook on low for six hours, or on high for two to three hours.

Season to taste with salt, but bear in mind that there is a fair bit of salt already from both the kimchi and the miso.

Serve with your favourite chilli toppings, such as fresh coriander, lime wedges, soured cream (plant-based, if need be) or cheddar.

Ferment: Simple Ferments and Pickles, and How to Eat Them, by Kenji Morimoto, is published by Pan Macmillan at £22. To order a copy for £19.80, visit the guardianbookshop.com