Slow Cooker Mediterranean Lentil Stew

Name: Slow Cooker Mediterranean Lentil Stew
Prep time: 20 min
Cook time: 3 h 10 min
Total time: 3 h 30 min
Cuisine: American
Ingredients: 5 cups water; 2.5 cubes vegetable bouillon, or more to taste; 2 cups dry lentils; 5 small carrots, peeled and diced; 2 medium potatoes, peeled and diced; 3 teaspoons ground cumin, or to taste; 1 teaspoon ground coriander; 1 tablespoon olive oil; 1 small onion, diced; 4 cloves garlic, minced; 0.5 (6 ounce) can tomato paste, or to taste; 0.5 teaspoon sea salt, or to taste; 0.5 teaspoon freshly ground black pepper, or to taste; 0.5 (8 ounce) package fresh spinach, torn