Put the spinach in a large bowl. In a small bowl, whisk the rice vinegar with 1-1/2 Tbs. of the soy sauce, the sugar, and 3 Tbs. water. Put the pork in a medium bowl and season with 1/2 tsp. salt. Toss with the remaining 1 Tbs. soy sauce, the sherry, and the cornstarch. Let sit for 10 minutes.
Heat 1-1/2 Tbs. of the canola oil in a heavy, 12-inch skillet over medium-high heat until hot. Add the pork and cook, stirring, until it loses its raw color and is just firm, about 2 minutes. Transfer the pork to a clean medium bowl.
To the skillet, add 1-1/2 Tbs. of the canola oil and the sesame oil, scallions, mushrooms, and bell pepper. Sprinkle with salt and cook, stirring, until the mushrooms and scallions soften and brown in places, about 3 minutes. Transfer the vegetables to the bowl with the pork and toss.
Still over medium-high heat, add 1 Tbs. of the canola oil and the ginger to the skillet and cook, stirring until very fragrant, about 30 seconds. Remove the skillet from the heat, add the vinegar-soy mixture, and stir well with a wooden spoon or spatula, scraping the pan to incorporate the browned bits. Whisk in the remaining 1/4 cup canola oil; the mixture will remain largely separated. Transfer the vinaigrette to a measuring cup and whisk to emulsify thoroughly (the cornstarch from the browned bits will help).
Toss the spinach with half of the vinaigrette (or enough to lightly coat). Portion among four plates, top with the pork and vegetables, and drizzle with some of the remaining vinaigrette (you may not need it all). Serve immediately.
Serve with Steamed Jasmine Rice.
nutrition information (per serving):
based on four servings;
sat fat g
Photo: Scott Phillips