sweet potato lentil stew

1 medium onion, diced
2 small tomatoes, diced
1 teaspoon minced fresh ginger
1 1/2 teaspoons turmeric
1 teaspoon cumin
1 teaspoon ground coriander
1/2 teaspoon ground cinnamon
1/8 teaspoon cayenne
Fine sea salt (optional)
2-3 medium sweet potatoes, peeled and cut into 3/4” cubes
7 cups low-sodium vegetable broth
1 cup brown or red lentils
Directions
Heat two tablespoons of the broth over medium heat in a large, deep pot. Add the onion and cook, stirring frequently, for two minutes or until the onion starts to soften. Stir in the tomatoes and ginger and cook for three minutes. Stir in the turmeric, cumin, coriander, cinnamon, cayenne, and a small pinch of salt, if using. Cook and stir for two minutes, then taste for seasonings; try to use only enough salt to heighten the flavors.
Add the sweet potatoes, broth, and lentils. Stir well, and bring to a boil over high heat. When the mixture comes to a boil, reduce the heat, cover, and simmer for 40 minutes or until the lentils and sweet potatoes are soft.