Irish Terriers are very quickly bored if you give them the same food every day.
We feed them a special kibble based on fish. 
But thats not all, every day we add something different to spice it up and
keep it interesting.
So cooked chicken, turkey, fish, macaroni, rice, patatoes,old bred, left overs,
always make sure there is no salt in the food you add, and dont forget vegs
and fruits like carrots, apple, banana.

If they catch a rabbit or mouse they will eat them raw, so they have
a natural desire for raw meat. The best you can do is give them
the fatty parts of your steak (raw) or buy twice a week a piece
of cheap steak to meet their desires for this.
(dont forget to worm them every 3 months)

In the old days they were fed for hundreds of years on table scraps
so imagine an old irish stew on a traditional little farm somewhere
in the mountains of Ireland and you have the impression how they
were fed.

We tried it all, barf the raw feeding, only wet food, only dry food
and came to the conclusion they thrive the best on what we
feeding them now.

something about drinks :

Always fresh water, it sounds easy but its very important
Till they are a year old we give them full goatsmilk, its very
good for the developing bones and overall structure.

Bones :

Its like this, that dental sticks don't do the job at all, for strong
white teath they need twice a week a proper bone.
So talk to your local butcher and ask him if he can help you out, oxtail is also brilliant.
Forget all the terrifying stories about feeding bones
its the only way to keep them in good condition, and otherwise
you end up for dental threathment at the vet and bills from over
200 pounds for a clean-up.
If you give them a bone always keep an eye on them and check
the bone now and than.

If you really want to play on save buy rawhide bones, if they get
soft take them away and give them back when they are hard again
so they will last much harder.