Soak the split peas overnight in a large bowl of water. The next day, drain them and set aside.
Finely chop the celery, onion, ginger and garlic.
Roughly chop the carrots.
Heat the oil in a saucepan over medium-high heat. Add onion, celery, ginger and garlic and gently sauté for 5 minutes.
Add the chopped carrots to the pan, then the tomato purée & spices. Stir for a minute, then add drained split peas and the stock.
Bring to a boil, then put a lid on and turn down the heat. Gently simmer for 45 minutes until the split peas are soft. Add more stock if needed.
When the peas are mushy, turn off the heat and add the fresh herbs.
Using a stick blender, pulse the stew into textured soup.
Add the spinach, reheat for a couple of minutes, then serve.