Heat the whole milk together with the dextrose and the low-fat milk powder.
Mix the egg yolk with the vinegar and stir until smooth. Pour the warm milk on top.
Heat the mixture while beating until the yolk starts to firm. Add butter and olive oil.
Next, add 20 g of tarragon and let this set in the refrigerator for 12 hours.
Remove the tarragon and freeze the mixture in Pacojet beakers or run it in the ice cream machine.