Mushroom and Walnut Meatballs in Tomato Sauce

General Fast With Oil Published August 02, 2026

Walnuts and mushrooms together do something that neither does alone — the mushrooms bring glutamate and moisture, the walnuts bring fat and a meaty bite. Bound with breadcrumbs and lentils, they hold their shape through a bake and a simmer and land somewhere genuinely satisfying.

The critical step is driving the water out of the mushrooms. Wet mushrooms make mushy meatballs. Cook them hard until the pan is dry and they have shrunk by half, and the mixture will roll cleanly.

Serve over pasta or polenta with bread. Roll them small for a crowd; they freeze raw and bake from frozen with ten extra minutes.

FASTING LEVEL: Fast With Oil
SERVINGS: 4 (makes about 20 meatballs)
TIME: 1 hour

INGREDIENTS

For the meatballs:
- 400g cremini mushrooms, finely chopped
- 3 tablespoons olive oil, divided
- 1 onion, finely diced
- 4 garlic cloves, minced
- 1 cup (100g) walnuts, toasted and finely chopped
- 1.5 cups cooked brown lentils (or 1 x 400g can, drained well)
- 1 cup (100g) dry breadcrumbs
- 3 tablespoons ground flaxseed mixed with 6 tablespoons water
- 2 tablespoons soy sauce
- 2 teaspoons dried oregano
- 1 teaspoon fennel seeds, crushed
- 1/2 teaspoon red pepper flakes
- Salt and black pepper

For the sauce:
- 2 tablespoons olive oil
- 4 garlic cloves, sliced
- 2 x 400g cans crushed tomatoes
- 1 teaspoon sugar
- 1 teaspoon dried oregano
- Handful of basil, torn
- Salt

METHOD

1. Heat the oven to 400°F (200°C). Line a sheet pan with parchment.

2. Heat 2 tablespoons oil in a large skillet over medium-high. Add the mushrooms and cook 10-12 minutes, stirring occasionally, until they have released their water and the pan is dry. This is the step that decides everything.

3. Add the onion and remaining tablespoon of oil. Cook 6 minutes until soft. Add the garlic, oregano, fennel, and pepper flakes and cook 1 minute more. Let cool 10 minutes.

4. In a large bowl, mash the lentils roughly with a fork — leave some whole for texture. Add the mushroom mixture, walnuts, breadcrumbs, flax mixture, and soy sauce. Season well with salt and pepper and mix thoroughly with your hands.

5. The mixture should hold a ball when squeezed. If loose, add breadcrumbs a tablespoon at a time; if dry, add a splash of water.

6. Roll into 20 golf-ball-sized meatballs and arrange on the pan. Bake 25-30 minutes, turning once, until firm and browned.

7. Meanwhile, make the sauce: heat the oil, cook the sliced garlic until pale gold, add the tomatoes, sugar, and oregano, and simmer 20 minutes until thickened. Season with salt and finish with basil.

8. Slide the baked meatballs into the sauce and simmer gently 5 minutes before serving.

NOTES

- For strict no-oil days: dry-cook the mushrooms in a nonstick pan, bake the meatballs on parchment without oil, and make the sauce with water in place of oil. Bake, do not fry.
- Ground flaxseed is the binder — do not skip it. Chia works too.
- Pecans or sunflower seeds substitute for walnuts.
- Leftover meatballs make a sandwich the next day that is better than it has any right to be.