Peel and dice the potatoes, trim the green beans, and chop the bell pepper, onion, and garlic.
Heat the olive oil in a large pot or deep skillet over medium heat. Add the potatoes and cook for 8 to 10 minutes, stirring occasionally, until they begin to soften and become lightly golden around the edges.
Add the green beans, bell pepper, onion, and garlic. Season with the thyme, salt, and black pepper. Cook for 7 to 8 minutes, stirring occasionally, until the vegetables begin to soften and become fragrant.
Pour in the tomato puree, soy sauce, and water. Stir well and bring everything to a gentle simmer.
Cover and simmer for 20 to 25 minutes, until the potatoes are fork-tender, the green beans are soft, and the tomato sauce has thickened slightly.
Remove the pot from the heat and sprinkle with fresh parsley. Let the stew rest for about 10 minutes before serving so the sauce can settle and thicken slightly.