Put the nasturtium seeds into a bowl and more than cover with water. Scoop off and discard any bits of dead leaf or other matter that float to the top.

Rinse in a sieve under a cold running tap then leave to drain.

Put the salt into a bowl and pour in the water.

Stir to dissolve the salt then stir in the nasturtium seeds.

Soak for 24 hours.

Sterilise a small jar:

Preheat your oven to its lowest setting.

Wash a small jar and and plastic-lined lid in hot, soapy water then rinse and leave to drain.

Put the jar and lid on a small baking tray in the oven and leave for 20 minutes.

Remove from the oven.

Drain the nasturtium seeds and dry on kitchen towel.

Pack them into the sterilised jar, leaving a gap approximately 1cm at the top.

Put the vinegar and sugar in a small saucepan along with the peppercorns and herbs if using.

Briefly heat to dissolve the sugar then take off the heat.

Pour the vinegar over the nasturtium seeds and put on the jar lid.

Store in a cool, dark place for 2-3 weeks before using as you would true capers: in salads, sauces, pasta etc.

Use within 12 months and store in the fridge once opened.