Season the lamb with half of the salt and pepper.

Heat 2 tablespoons of olive oil in a skillet over medium-high heat.

Brown the lamb in the skillet.

Transfer the browned lamb to a 3.5-quart crock pot.

Sauté the onions in the remaining 1 tablespoon of olive oil until translucent (3-5 minutes).

Add the garlic and oregano to the onions and cook, stirring, for approximately 1 minute.

Add the drained tomatoes to the onion mixture and simmer, smashing the tomatoes as you stir.

Pour half of the tomato mixture over the lamb in the crock pot.

Place the potatoes in a layer on top of the tomatoes and season with salt and pepper.

Add a layer of green beans, then eggplant, and finally zucchini.

Season each vegetable layer lightly with salt and pepper to your taste.

Pour the remaining tomato mixture on top of the vegetables.

Add the bay leaves.

Cover the crock pot and cook on high for 4 hours, or until the lamb is tender.

Remove the bay leaves before serving.

Serve hot.