Coat the beef chunks evenly with flour and some freshly ground pepper inside a bowl or plastic bag.
Warm the cooking oil in a large Dutch oven over medium-high heat and brown the floured beef pieces in batches to avoid overcrowding.
Set the browned beef aside on a plate once all sides have a nice crust, about five minutes per batch.
Reduce the heat to medium and add onions, garlic, red chili pepper, leek, celery, carrots, and dried thyme to the pot; stir for a few minutes to lift the browned bits from the bottom.
Pour in the red wine to finish deglazing the pot, scraping any remaining flavorful bits loose.
Return the browned beef along with any juices on the plate back into the pot.
Add beef stock, diced tomatoes, salt, and pepper; mix everything well.
Cover the pot and bring the stew to a boil, then immediately reduce the heat to the lowest setting.
Sprinkle fresh thyme leaves and parsley over the stew and toss in the bay leaf, then cover and let it simmer gently for about two hours, stirring occasionally.
About 15 to 20 minutes before serving, sample the stew and adjust seasoning as desired.
Once cooked, the broth should be rich brown and the beef tender enough to fall apart easily.
Serve hot over plain boiled potatoes for a rustic and warming meal.