In a large saucepan, sauté the onion and garlic in the oil over a medium heat until slightly
softened, about 3-4 minutes. Add the drained beans, spinach, tomatoes and sage to the pan.
Add 150 ml / 1/4 pint of the stock. Cover and simmer over a very low heat for about 15 minutes,
topping up with stock as necessary. Season to taste with salt and pepper.
To serve, put a round of toasted bread into each serving bowl and ladle some of the beans over the top.