Somewhat Mediterranean Lentil Soup

Somewhat Mediterranean Lentil Soup

1 cup brown lentils (check them over for tiny rocks)
1/4 cup olive oil
1 diced onion
minced garlic, to your garlic threshold. I think this soup should knock out vampires at twenty paces.
1 peeled, diced sweet potato
1 package frozen spinach (thawed, with excess moisture squeezed out)  or equivalent fresh (you're on your own, and why are you using fresh spinach in a soup? I am not angry, but I am very disappointed.)
1 lemon
salt and pepper to taste
about a quart of water; you may add more
(optional vegetarian bouillon cube)  

Start with the olive oil and saute the onion. Get it nice and translucent, and at the very end, add the garlic. Give it a good stir and add the water, the lentils, the optional cube, and the sweet potato. Bring it to a boil, then down to a bubbly simmer. At twenty-five minutes, check both the water and the sweet potato. The mixture should be soupy, and the sweet potatoes should be tender. You may have to add more water and increase the time for this. When sweet potatoes are done, or close to done, add the thawed spinach, and allow everything to come up to temperature. Finish with a nice strong squeeze of lemon juice.

You could garnish this with a dollop of plain Greek yogurt, or a sprinkle of feta cheese.