Heat vegetable oil in a medium saucepan over medium heat.

Add chopped onion to the saucepan and sauté for 4 to 5 minutes, or until browned.

Add chopped cauliflower florets, carrot slices, and 1/2 cup of water to the saucepan.

Bring the mixture to a boil.

Reduce heat to medium-low, cover the saucepan, and simmer for 10 to 12 minutes, or until vegetables are very tender.

Add 2 to 3 tablespoons of water if the pot becomes too dry before the vegetables are cooked.

Drain off any excess liquid from the saucepan.

Transfer the cauliflower mixture to a food processor.

Add white miso and ground sage to the food processor.

Puree the mixture for 2 to 3 minutes, or until smooth.

Season with salt and pepper to taste, if desired.