Here’s how:

Boil your potatoes the day before (or in the morning) and pop them in the fridge to go cold.

When potatoes are cooked and then chilled, they transform into a resistant starch, which also acts as a prebiotic, feeding your good gut bacteria. 

Trim and cut your celeriac, then boil until super tender, just like the potatoes.

Drain everything, then bung the potatoes in with the celeriac. Pop back on the hob just to gently heat through.

Mash together with a good drizzle of olive oil, a knob of butter, and some salt and pepper.

(If you’re feeling creative, add a spoon of mustard or a sprinkle of cheese, but try it plain first, it might not need a thing!)

⸻

To serve: 

I paired mine with a homemade celeriac-top tartar sauce, simply mix:

mayonnaise

finely chopped celeriac tops

capers

I served it with a piece of fish and some steamed greens