This Japanese vegetable stew of root vegetables, Chinese cabbage and squash is one of my favorite cold weather dishes. As they cook, the vegetables create a rich broth that is enhanced by umami-rich miso paste and a vegetarian dashi.
8-24 hours before you start cooking, start making the dashi (see separate recipe below). If you used whole shiitake mushrooms in the dashi, save them to use in the stew.
If you didn't get the 8-24 hour head-start, you can make a quick version of the dashi (see notes in the separate recipe).
It is probably best to prepare all of the vegetables ahead of time, but if you are a quick slicer, they could be prepared as you go while the previous vegetables are cooking. In that case, the vegetable groupings are 1) leek; 2) carrot; 3) sweet potato and squash; 4) white part of cabbage and mushroom; 5) green part of cabbage.
Mushrooms: If mushrooms are dry, soak them in hot water to soften, then drain, saving the soaking water to add to the stew after pouring it through a coffee filter or very fine strainer. Slice the mushrooms into strips. Put the strips into a bowl large enough to also hold the white parts of the napa cabbage.
Leek: After cutting off the green part and root end, quarter the leek lengthwise. Slice into 1/4" pieces. Put the chopped leeks into a bowl of water and agitate to remove any sand or grit. After a few minutes, scoop out the leeks to leave behind sand and grit.
Carrots: Cut the carrots into 1/2" long slices (a roll cut is best here). Put the cut carrots into a bowl.
Sweet potato: Cut the sweet potato into chunks that can fit onto a spoon (about 1/2" on a side). Uneven is OK (and unavoidable). Put the sweet potato in a bowl large enough to also hold the squash.
If using a kabocha squash, peel part or all of the squash (the peel is edible). If using another squash (like butternut), peel it. Cut the squash into bite size pieces. Uneven is OK (and unavoidable). Put the squash in a bowl with the sweet potato.
Napa cabbage: Separate the white part of the napa from the leafy part. Roughly chop the green parts of the napa cabbage, with the goal of pieces that will fit on a spoon without trouble (no long dangling).
Combine the white parts with the mushrooms. Put the green pieces into a separate bowl.
Heat oil over medium heat. Add the leeks. Cook for 5 minutes until soft, stirring frequently.
Add carrots and broth (dashi). Stir. Bring to a boil, then reduce heat to a gentle simmer. Cover, cook for 5 minutes.
Add the sake and cook for about 1 minute, covered.
Add squash and sweet potato. Stir. Cover, cook for 5 minutes.
Add white part of napa cabbage and mushrooms. Stir. Cover, cook for 5 minutes.
Extract about 1 cup of the liquid from the pot into a heat-proof container (like the pan used to make the dashi).
Add the miso to the extracted liquid and whisk to distribute it evenly. You want to avoid lumps.
Pour the liquid / miso mixture into the pot.
Add the soy sauce and reduce the heat to low.
Add the leafy parts of the napa cabbage. Stir. Cover, cook for 5 minutes.
The type of miso you choose will influence the final flavor: red is bold and hearty; white is often sweet and mellow. (I usually choose red.)