If you have time, you could make this soup with dried white beans instead of the canned ones; they'll need to be soaked overnight and cooked for longer.
- 2 tbsp extra-virgin olive oil, plus extra for drizzling
- 1 Spanish onion, thinly sliced
- 2 garlic cloves, finely chopped, plus 1 extra clove, halved, for rubbing
- 1 tsp dried chilli flakes, or to taste
- 1.2 kg canned white beans, drained, rinsed
- 1 litre vegetable or chicken stock (4 cups)
- 2 fresh bay leaves
- 1½ tbsp red wine vinegar, or to taste
- 8 thick slices sourdough bread
- To serve: coarsely chopped flat-leaf parsley and oregano
- 1Heat olive oil in a large saucepan over medium-high heat, add onion and garlic, stir occasionally until tender (4-5 minutes), add chilli, stir to combine. Add beans, stock and bay leaves, simmer for 15 minutes, then pulse with a hand-held blender until partially puréed. Add vinegar, season to taste and keep warm.
- 2Meanwhile, preheat a char-grill pan over high heat. Drizzle both sides of bread slices with a little olive oil, season to taste and char-grill, turning once, until toasted (1-2 minutes each side). Rub crostini with remaining garlic and place one slice in each serving bowl. Ladle over hot soup, scatter with herbs and serve with remaining crostini.