Spaghetti Arrabbiata ('Angry' Pasta Sauce) - The Pesky Vegan

Ingredients

• 7 oz (200 g) dried spaghetti ((gluten-free if necessary))
• 1-2 tablespoons extra-virgin olive oil
• 1 medium onion, finely chopped
• 3 garlic cloves, finely chopped
• 1 teaspoon dried chilli flakes ((plus more to taste))
• 1x 14 oz (400 g) tin tomatoes ((good-quality if possible – see notes))
• 1 bay leaf
• 2 teaspoons vegan balsamic vinegar ((or red wine vinegar – optional))
• Salt and pepper to taste
• Pasta cooking water
• Small handful fresh parsley