I've got this soup mastered since it's the hb very best favorite. I make it often.

3 stalks celery
1 carrot (small chop)
1 med onion
Ham base 1 large tbls.(as better than bouillon)
Saute vegs in a 6 qt. soup pot w/2 cups water.

Then add:
2 cups split peas
1 cup barley.
1/2 stick butter (or more)
tbls oregano and 2 tbls ground thyme.
water to fill 5 quarts.

Bring to boil, then I let mine simmer for hours (stir often) until barley/peas fall apart. Add a couple cups of small diced ham last hour