Heat oil in heavy large pot over medium-high heat. Add onions and sauté until translucent. Add next 7 ingredients stopping at crushed red pepper and sauté, about 1 minute. Stir in lentils and sauté for about 2 minutes.
Add chicken stock, bay leaf and honey and bring to boil. Reduce heat to medium-low and simmer uncovered until lentils are almost tender, adding more water by 1/2 cup at a time to thin soup, to desired consistency, about 15 minutes. Add potatoes/root vegetables and simmer soup another 10 minutes or until lentils are tender and potatoes are done to taste. Turn off fire.
Add spinach. Season soup with salt and pepper. (If making1 day ahead, chill soup uncovered until cold, then cover and keep refrigerated. Rewarm soup over medium heat, thinning with water if desired before serving.)
Tomato based- When adding garlic add 2 Table. tomato paste and sauté with spices. After adding stock then add 1 cup of diced tomatoes.