Heat oil in a tagine or dutch oven over medium heat.
Add onion and cook until softened.
Season with salt and pepper.
Add garlic, ginger, turmeric and cumin, and cook for 2 minutes.
Add in potatoes and coat by tossing.
Next, add carrots and fennel and stir until well combined.
Cook for 3 minutes.
then add tomatoes.
Transfer all ingredients into slow cooker.
Pour vegetable broth to cover all vegetables.
Cover and cook on high for 3 hours.
Taste to season.
Add in olives and lemon and half the cilantro leaves.
Transfer to serving dish and sprinkle remaining cilantro leaves.
Serve and enjoy.