Place the lentils in a strainer and rinse them under cool water. Set aside.

Heat the oil in a medium pot over medium heat and add the onion and celery. Fry until soft and transparent.

Add the garlic and carrots and fry until the carrots are just tender - about 5 minutes.

Add the tomato paste, bay, cumin and thyme and fry for another 2 minutes until the tomato paste darkens in color a bit.

Add the lentils, diced tomatoes and vegetable stock. Raise the heat to bring to a boil then reduce to a simmer and cover the pot.

Simmer, stirring from time to time to ensure the lentils don’t stick to the bottom of the pan, until the lentils are tender all the way through but not falling apart or mushy - 15 to 20 minutes.

Stir in the spinach, lemon juice and salt to taste. Once the spinach has wilted, it’s ready to serve.