Heat the oil in a large pan over a medium heat. Add the diced bacon and fry for 3-4 minutes until it starts to crisp up and release its fat.
Add the chopped onion and carrots to the pan and cook for 5 minutes, stirring occasionally, until the onion has softened.
Stir in the crushed garlic and smoked paprika and cook for 1 minute until fragrant.
Add the rinsed red lentils, stock and bay leaf. Bring to the boil, then reduce the heat to low and simmer for 20 minutes until the lentils have broken down and the soup has thickened.
Remove the bay leaf and season with salt and black pepper to taste. The bacon is already salty so taste before adding salt.
Blend half the soup with a stick blender for a creamier texture, or leave it chunky if you prefer. Serve hot with crusty bread.