Georgian plum sauce (tkemali)

A couple of years ago, I had one of the most interesting travel experiences of my life, up there with Tibet in my top travel rankings. Georgia, the country not the region, is unspoiled, cheap, different and has an amazing food and drink culture. If like me, you love sour flavours, they use unripe green plums to make a green sauce called tkemali and red ripe plums for a red version. It's like an acidic and sophisticated version of ketchup, beloved by Russians as well as Georgians. I used unripe yellow plums from South Africa to make this sauce to accompany roast cod. In Georgia they use it for potatoes or meat.
In terms of ingredients, the only difficulty is finding the herb Pennyroyal, the nearest equivalent being mint or spearmint. You also use Summer or Winter Savory, a bit like a peppery Marjoram, which we have grown at the Secret Garden Club with success. But I made this sauce without these herbs and it tasted similar to what I enjoyed in Georgia.

1 kilo of unripe plums ( yellow or green), blanched, skins removed
5 cloves of garlic, minced Handful of fresh green coriander, Handful of fresh dill, Small handful of fresh Pennyroyal or mint Small handful of Summer or Winter Savory if you can get hold of it Juice of 1 lemon 1 tbsp of sugar Salt to taste I merely whizzed this lot in a powerful blender such as a Vitamix but you could also follow the more complex and probably more authentic recipe in this blog. It is served cold with fish, grilled aubergines, potato or meat.

Comments appreciated...thanks