3 tbsp. extra-virgin olive oil
5 onions, thinly sliced
3 shallots, thinly sliced
2 cloves garlic, crushed
2 leeks, white and light green parts only, thinly sliced on the diagonal
Kosher salt and freshly ground black pepper, to taste
2 tbsp. sherry vinegar
1/4 cup madeira
6 cups vegetable stock
1/2 tsp. black peppercorns
3 small sprigs fresh thyme
1 bay leaf
1 tbsp. white soy sauce
1 1/2″ piece ginger, peeled and thinly sliced
1 5″ piece kombu
8 oz. spaghetti, preferably made with spelt
1 oz. shelled sea urchin (optional)