Layered Mashed White and Sweet Potatoes with Greens

Another recipe from Caldwell Esselstyn's Prevent and Reverse Heart Disease.

Ingredients
6 medium white potatoes, peeled and cut into 1-inch chunks (if you don't mind skins, don't peel)
3/4 - 1 cup oat or nonfat soy milk
2 medium sweet potatoes, peeled and chunked
1 large onion, chopped (1 cup)
4 cups packed collard greens, finely chopped and steamed
3 cups chopped Napa cabbage, steamed (about 1/2 cabbage)
1/4 cup finely chopped fennel (not necessary to steam)
cilantro, chopped
1 tbs lemon juice, or to taste

Directions

1. Cook white potatoes in a large pot of boiling water until soft. Drain and transfer to a large bowl. Mash, adding milk, until no longer stiff.

2. Steam or boil sweet potatoes until soft. Drain, and transfer to another large bowl.

3. Stir-fry onions in a nonstick pan over medium-high heat until brown, adding water or broth as necessary. Add onions to mashed white potatoes along with collard greens. Mix well.

4. Add cabbage and fennel to sweet potatoes. Mix well.

5. Put a single layer of white potatoes in a 9 x 11-inch baking dish.  Follow with a layer of sweet potatoes. Finish with a layer of white potatoes.

6. Preheat oven to 350 degrees.

7. Bake for 30 minutes. Sprinkle with chopped cilantro and serve.

[Edited 3/5/13: I didn't care for this.  It was bland and used an obscene number of pots and bowls.  I served chik'n fingers with it, but Sameer ended up heating up a frozen pizza afterward anyway.]