Slow Cook Lentil-Sweet Potato Soup

From many trial and errors and several retakes and revisions, here is the final recipe for my Slow Cook Lentil-Sweet Potato Soup. It is hardy, thick, and savory, with a reddish, slightly sweet broth. Note: this recipe is adapted from the following recipe at About.com: http://vegetarian.about.com/od/soupssalads/r/crockpotlentil.htm

• Ready In: 10 hrs 20 mins
• Serves: 7-9
• Yields: 5 quarts

Ingredients

• 2  cups lentils
• 1  cup water
• 4  cups vegetable broth or 4  cups  vegetable stock
• 1  medium onion, diced
• 1 -1 1⁄2 tablespoon  granulated onion powder
• 2  carrots, chopped chopped or minced
• 2 -3  garlic cloves, minced
• 1 -1 1⁄2 tablespoon  granulated garlic powder
• 1  teaspoon salt
• 1⁄2 teaspoon black pepper
• 1⁄2 teaspoon oregano
• 1 (14 ounce) can diced tomatoes
• 1⁄2-1  cup sweet potato puree

Directions

1. Clean and presoak the lentils for a few hours, two to three is sufficient, over night works well also. The lentils will easily drink up two cups of water.
2. Strain them, and dump them and all of the other ingredients into a 6 quart or larger slow cooker. (A 5 quart might work, but it would be a tight fit.)
3. Cook on low for 10 hours or high for 5 hours. I usually do a combination of the two settings (e.g., 6 hours on low and then 2 hours on high).
4. NOTE: Three medium (baseball sized) sweet potatoes, chopped, can be substituted for the sweet potato purée, but the later seems to sweeten and thicken the overall soup significantly. The same with the carrots, where mincing them does seem to impact the color, flavor, and texture a bit.
5. NOTE: I have yet to try red lentils, so, if some brave individual does, I've appreciate hearing about how it turns out and what adjustments are required.