Pierce potatoes in several places with a sharp knife. Cook in the microwave, turning once, until tender, about 10 minutes. Cool until easily handled, about 5 minutes. Peel 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. Cook and stir onion in the hot oil until golden, 5 to 10 minutes. Remove from heat.
Combine potato cubes, onion, green beans, frozen carrot blend, and frozen lima beans in a large bowl. Toss gently to mix together. Spread in the prepared baking dish.
Combine 1 1/2 cup water, 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; 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 gravy into the baking dish; spread with a spatula to coat vegetables evenly. Cover with aluminum foil.
Bake in the preheated oven until gravy just starts to bubble, about 12 minutes.
Stir baking mix, almond milk, vegetable oil, and salt in a bowl until dough is just moistened. Uncover baking dish and drop spoonfuls of biscuit dough over the gravy.
Return to the oven and bake, uncovered, until biscuits turn golden brown, 14 to 16 minutes.
