I’m always banging on about how recipes are templates and you can make informed substitutions. The version I made recently from the below recipe is a prime example. I used brown onion, cauliflower and broccolini stalks because it was what I had in the house. I also halved the recipe with no issues.
I present the actual recipe below but you should feel comfortable to freestyle.
Put the chopped vegetables in a ceramic bowl and toss with 2 tbsp fine salt. Leave, covered at room temperature, for 4 hrs. Drain veg, rinse under cold water and drain really well.
Place 100ml of vinegar in a bowl with the mustard powder, coriander seeds, mustard seeds, cumin, turmeric and flour. Mix well. Heat the remaining 500ml vinegar, sugar, bay leaves and a pinch of salt until the sugar dissolves, then pour in the mustard/vinegar mix, simmering and stirring for 5 mins until the mixture thickens a bit.
Fold in the drained veg, heat for 1 min taking the edge off the veg, then remove from the heat, and pack into sterilised jars. Seal and leave in a cool dark spot for six weeks or up to three months before opening.
Once open, keep in the fridge and use within four weeks.