High Tea

This is easiest done in the village.

A pasty and a slice of cake can be bought from Iris in the bakery

Then in the Village Hall opposite there's a tea - note the tea looks like a big green metal tin of tea on one of the tables near the entrance (i.e. not a cup of tea). Alternatively you can barter with Alf in the pub for one.

Once you've got all three in your inventory you can consume them one after the other and the achievement will pop immediately.