Pierce potatoes in several places with a sharp knife.

Microwave potatoes on high, turning once, until tender, about 10 minutes.

Cool potatoes until easily handled, about 5 minutes.

Peel potatoes and cut into cubes.

Preheat oven to 425 degrees F (220 degrees C).

Grease a 9x13-inch baking dish.

Heat olive oil in a small skillet over medium heat (optional).

Cook and stir chopped onion in the hot oil until golden, 5 to 10 minutes (optional).

Remove from heat.

Combine potato cubes, cooked onion (if used), cut green beans, frozen carrot, peas, and corn blend, and frozen lima beans in a large bowl.

Toss gently to mix together.

Spread vegetable mixture in the prepared baking dish.

Combine 1 1/2 cup water, raw cashews, liquid aminos, cornstarch, onion powder, white pepper, and garlic powder in a high-powered blender.

Blend until completely smooth.

Add remaining 1 1/2 cup water to the blender.

Blend until thoroughly incorporated.

Pour cashew mixture into a saucepan over medium-high heat.

Cook, stirring constantly, until gravy is slightly thickened, about 5 minutes.

Pour cashew gravy into the baking dish.

Spread with a spatula to coat vegetables evenly.

Cover the baking dish with aluminum foil.

Bake in the preheated oven until gravy just starts to bubble, about 12 minutes.

In a separate bowl, stir together baking mix, almond milk, vegetable oil, and salt until dough is just moistened.

Uncover the baking dish.

Drop spoonfuls of biscuit dough over the gravy.

Return to the oven and bake, uncovered, until biscuits turn golden brown, 14 to 16 minutes.