Put oil at bottom of slow cooker.

Layer veggies in slow cooker, alternating colors a few times (orange, white, orange, white, orange). Top with pineapple rings, if desired.

Mix remaining ingredients in a small bowl, then drizzle over the top. Do not add water. Cook on low for eight hours.

Transfer to a pan to freeze, if desired. The veggies can also last in the fridge for about five days. Reheat covered, but you can uncover for about 20 minutes if you desire a more roasted texture.

Optional: Add sliced almonds and/or a few shakes of dried basil or cilantro for garnish when serving.