Mix the tomatoes, cucumber, red pepper, onion, garlic, and breadcrumbs. Add the vinegar, stock, thyme and 12 of the basil leaves. Marinate 12 hours in a covered glass bowl in the fridge. Purée, and season to taste with salt, pepper, and cayenne pepper. If too acidic (and this will depend on the tomatoes you’ve used), add a little honey. Serve cold with the remaining basil leaves shredded and scattered over top along with some croûtons.