Traditional Recipe
250g/8oz carrots, diced
250g/8oz turnips, diced
2 onions, diced
1 stick celery, diced
white of 1 leek, sliced
75-125g/3-4oz pearl barley
125g/4oz dried peas, soaked for 4-5 hours
salt and pepper
about 2.3L/4pt lamb or mutton stock
kale or other bitter winter greens, chopped (optional)
Add all the ingredients to the stock and simmer gently for a couple of hours, making sure that the peas become mushy and the barley expands and becomes soft and white.
If you wish, add a few ounces of kale 10 minutes before the end of the cooking time. Check the seasoning and serve.
Recipe taken from RampantScotland.com
Modern Take
There isn't really a modern take that I can find. Its a pretty simple recipe.
What is it?
Scotch broth is a hearty soup with whole grains and mutton (I have had it without meat also). It is very common over here and is often seen in restaurants and cafes. The bakery I work at serves it quite often and refers to it simply as broth.
I should think that you could use beef broth or even chicken or vegitable broth if, like me, you don't care for mutton.