To roast the peppers, preheat the oven to 200°C (380°F) fan oven / 220°C (425°F). Cut the peppers into quarters, place on a baking tray and drizzle lightly with oil and season with salt and pepper. Roast for 20 minutes until soft and lightly charred. Allow to cool to the touch before removing the skins and chopping.
To make the soup - Heat the oil in a Dutch oven or large pot over a medium high heat and add the onion with a generous pinch of salt. Cook for about 5 minutes then add the garlic, oregano, cumin, rosemary and basil. Cook for about 30 seconds to a minute, stirring to make sure the spices don’t burn.
Stir in the chopped roasted peppers and lentils, then pour in the tomatoes and stock. Bring to a boil then lower the heat and pop a lid on. Cook for 15-20 minutes, until the lentils are cooked and soft.
Blend the soup using an immersion blender, or allow to cool and transfer to a blender in batches. (My personal preference is to half blend the soup so it is nice and creamy but still has some chunks for a bit of bite. You can also blend until completely smooth or leave chunky and not blend at all.)
Stir through the lemon juice, zest and fresh parsley. Add additional salt to taste if necessary.