In large pan, cover cheaptest cut of pot roast (cut in small pieces) with water and bring to a boil. Skim off the scum. Reduce heat so that meat simmers. Add several beef bouillon cubes (I usually use about 10 for a very large pot.) Cut up 1 or 2 onions in chunks. Dice 1 or 2 stalks of celery. Peel and slice 3 or 4 carrots. Put all vegetables in with meat and simmer for 2-3 hours. Add 3/4-1 cup of barley and continue cooking for about 45 minutes. Add 1 can of peeled tomatoes, cut in chunks, juice and all. Also add about 1/2 package frozen mixed vegetables. Cook for about 20 minutes until vegetables are tender.
Note: I prefer making this the day before I actually plan to serve it. When refrigerated the grease will harden and can be thrown out.