Irish Stew is very simple to make and I make it the same way as I rememer my Great Grandmother making it except that she used Mutton not lamb and we didn't have celery.
You will need Lamb (chops or pieces), water, some potatoes (three or four), about four carrots, some onions, a couple of sticks of celery, a little butter & oil, salt, pepper, parsley, and thyme. My Great Grandmother never measured anything, she just threw everything into a big heavy pot that sat on a hook, for the whole day, hanging over the fire. Her stew is still the best stew I've ever tasted. My Grandmother likes my stew and says it tastes very like her mother's ... praise indeed.
Here is how to make up the stew:
Heat a little butter and oil in a heavy pot over a hot ring until it sizzles not burns, throw in the lamb, one roughly chopped onion and season with the Salt & Pepper. Toss around the lamb and onion until they are brown (should only take a few minutes). Now throw in some whole peeled potatoes (about three or four you can halve them if you like), the carrots (peeled and chopped diagonally in fairly large slices), three or four whole peeled onions (or again half them if you like), the sticks of celery (about three or four chopped into fairly large pieces), the parsely (a good handfull chopped), and about four leaves of thyme (pulls the leaves from four stalkes). Mix it all around with a wooden spoon and pour in Water until all the ingridients are well covered. Bring to a simmer, turn down until the water barely bubbles, leave for three to four hours on a low heat. Serve garnished with more parsley and Irish Soda or Brown Bread.
Remember, "a stew boiled is a stew spoiled". Of course the reason we leave the stew cooking for so long is that in the past, when we were poor and couldn't afford lamb, we used Mutton which needed to cook slowly for longer in order that it would become tender. Lamb doesn't really need to cook slow or for so long, but I guess old habits die hard. (Just as well, I published that recipe in 2000 in the middle of the Celtic Tiger, but now I guess we'll be going back to mutton and no harm).
TIP stew always tastes better the next day.