Season diced beef with salt and pepper, and dust with a tablespoon of flour.
Heat a drizzle of olive oil in a casserole pot and brown the beef in batches. Transfer to a plate.
Reduce heat to medium-low, add a little more olive oil and saute the onions and garlic for 1-2 minutes till fragrant then add the carrots and celery. When vegetables have softened, return the beef back into the pot then add the water, reserved liquid from beans, tomatoes, thyme, chilli flakes (if using) and stir to combine.
Bring to a simmer, cover with a lid and place in the oven to cook for 1.5 hours. In the last 30 minutes, add the cannellini beans and silverbeet. Season to taste.