Set Instant Pot on sauté. Add oil and warm for a minute. Add onions and cook for 1–2 minutes. Add the celeriac root, parsnips, and sweet potato. Cook until lightly browned, about 3–4 minutes. Add the lentils and broth, and pour in an additional 5 cups of water. Add salt, pepper, cumin, and granulated onion and garlic. Press cancel on sauté function, seal lid, and cook on high pressure or soup setting for 20 minutes. Turn off setting and allow pressure to release naturally. Once slightly cooled, blend with an immersion blender or regular blender. Adjust water based on the consistency desired, adding more water for a looser texture. Water can be evaporated by turning on the sauté function and mixing often.

Garnish with a sprinkling of nutmeg, chopped parsley, and a drizzle of olive oil.

Preheat a large stockpot or dutch oven over medium heat. Once hot, add oil and sauté onions for 1–2 minutes. Add celery root, parsnips, and sweet potato. Cook until lightly browned, about 3–4 minutes. Add lentils and broth, and pour enough water to cover mixture by 1–2 inches. Add salt, pepper, cumin, onion, and garlic. Bring to a boil and cook 3–4 minutes before reducing to a simmer. Cook, covered, until vegetables are easily pricked with a fork. Remove from the heat and blend.