Season the beef chunks with salt, pepper, and paprika. Heat olive oil in a large pot over medium-high heat. Sear the beef in batches, about 2 minutes per side, until browned on all sides. Work in batches to avoid crowding the pan. Set aside when done.

In the same pot with the leftover oil and browned bits, add the sliced onion. Cook until golden and caramelized, about 5 minutes. Add minced garlic and thyme, stirring constantly for about 30 seconds until fragrant.

Pour in the soy sauce and browning sauce, scraping the bottom of the pot to release caramelized bits. Return the beef to the pot and stir. Reduce heat to medium-low and simmer for about 20 minutes, stirring occasionally, until the beef is tender.

Cut potatoes into bite-sized cubes and toss with olive oil, salt, and pepper. Heat a skillet over medium-high heat and add the potatoes. Cook for 15 to 20 minutes, stirring occasionally, until golden and crispy on all sides.

Combine shredded cabbage, diced cucumber, and diced tomato in a bowl. Toss with mayonnaise, salt, and pepper until evenly coated. Prepare just before serving for maximum crispness.

Divide the brown stew beef among plates. Add crispy potatoes on the side and top with a heap of fresh slaw. Serve immediately.