Oshitashi is a a staple appetizer in Japanese restaurants, and, I imagine, in Japanese homes as well. There are many variations of this dish; here’s one I particularly like.
3 T sesame seeds, toasted, plus extra for garnish, optional
1 large bunch spinach, washed and stemmed
1 1/2 T toasted (dark) sesame oil
1 1/2 T soy sauce
1 1/2 T unseasoned rice vinegar
1 1/2 T mirin; or sweet sherry; or 1/2 t sugar dissolved in 1 1/2 T dry sherry, white wine, sake
1. To toast sesame seeds: put into a small skillet over very low heat. Stir occasionally until the seeds release their fragrance and darken in color. Be careful, they can burn quickly! Once they are toasted remove the pan from the heat and transfer the seeds to a plate to stop the toasting.
2. Cook the spinach–either by steaming or in a pot of boiling water. Do not cook for long, just until wilted, a minute or so. Drain and squeeze out as much excess water as you can, first with a wooden spoon, and then, when cool enough to handle, your hands. Coarsely chop and transfer to a serving bowl.
3. In a small bowl, whisk together the sesame oil, soy sauce, vinegar, and mirin. Add to spinach along with the sesame seeds and toss to combine. You can serve this as is, or you can make individual portions by putting the dressed spinach in a small ramekin, then flipping it over onto a small plate. Hopefully the spinach will retain the shape of the ramekin, making for an attractive presentation. Garnish served portions with additional toasted sesame seeds, if you like.