Prepare the base: Melt the butter with the olive oil in a large stockpot over medium heat.
Sauté the aromatics: Add the onions (or leeks/shallots) and sauté for 5–7 minutes until translucent and lightly golden.
Add garlic and herbs: Stir in the minced garlic and thyme leaves (if using). Cook for 1 minute until fragrant.
Deglaze with wine: Pour in the white wine, letting it cook for 2–3 minutes to allow the alcohol to evaporate.
Cook the mushrooms: Add the mushrooms to the pot and sauté for 3–4 minutes until softened.
Simmer with sunchokes: Stir in the sunchokes and pour in the stock. Add the bouillon to taste and mix well. Bring to a boil, then reduce the heat to medium-low. Cover and simmer gently for 20 minutes, or until the sunchokes are fork-tender.
Blend the soup: Use an immersion blender to puree the soup directly in the pot, or transfer it carefully to a blender. Blend until smooth, or leave some texture if preferred. Be cautious when blending hot liquids!
Season to taste: Stir in salt and freshly ground black pepper, adjusting to your taste.
Prepare Sunchoke Chips: Thinly slice 2–3 sunchokes using a mandolin. Heat olive oil in a pan to 350°F (175°C). Fry the slices until deep golden on both sides. Remove with a slotted spoon and sprinkle with salt. Be sure to make plenty, these are the crowning jewel and deliver beautiful texture.
Finishing Touches: Garnish the soup with pepitas, fresh or sautéed mushrooms, and crispy sunchoke chips for added texture and flavor.
Serve and enjoy: Ladle the soup into bowls and top with your chosen garnishes. Serve warm with crusty bread or herbed crackers.