Mulberries vary in sweetness, so I have provided a range for the sugar. Start with the lower amount, and taste the curd after about 15 minutes of cooking. You want it to be tart, but not so tart it makes your tongue shrivel. Add more sugar at this point if required. I make this in the Thermomix as it is easier. However I have also provided instructions to make this curd on the stove top. If you don't have fresh mulberries, this recipe will work just as well with frozen berries. You could also substitute other berries for the mulberries if you prefer. This curd will keep for up to three weeks in the fridge.