Remove outer leaves from cabbage, about 6 layers, trim tough ribs. Save remaining cabbage.
In a large pot or Dutch oven, bring 3 quarts of water to a boil over high heat, add cabbage leaves and cook until slightly softened and easier to work with (push under water with tongs), about 3-5 minutes.
Remove cabbage from pot with a slotted spoon (do not get rid of water) and place in a strainer to drain.
Add onions to water until just wilted, about 10 seconds, drain and pat dry with paper towel.
Preheat oven to 350 degrees F.
In a small bowl or cup, mix the thyme, black pepper, and 1 teaspoon of salt. Rub evenly over pork roast.
Wrap pork in cabbage leaves and secure in place with green onions (you will probably have to tie 2 green onion leaves together so it is long enough to fit around entire roast).
Place pork in a 14 x 10 inch roasting pan; pour bouillon dissolved in hot water into pan.
Insert meat thermometer in center and roast until temperature reads about 155 degrees F, about 1 hour. Baste pork occasionally with juices from pan.
In the meantime, place potatoes in a pot with enough water to cover and boil over high heat. Reduce heat to low, cover, and simmer until soft, about 20 minutes. Drain and carefully cut into 1/2 inch cubes (they will be hot).
Coarsely slice remaining cabbage.
In a large pot, heat oil over medium high heat; add cabbage, caraway seeds, and remaining 1/2 teaspoon of salt, sauté until tender crisp. Add potatoes and heat thoroughly. Place onto a large serving plate and keep warm.
In the same pot, warm the cherry tomatoes over medium high heat until thoroughly heated; set aside.
When pork is done, remove from oven and place on platter with cabbage.
In a small cup, mix the water and cornstarch then add into the drippings of the roasting pan. Pour into a small pot and bring to a boil, continue boiling for 1 minute, skimming any visible fat. Spoon over pork and serve with tomatoes.