Sauté minced garlic with canola oil in a large pan on medium-high until fragrant. Add baby bok choy and cook until tender. Season with soy sauce. Sprinkle with chopped toasted cashews.
Boil 1 cup white vinegar with 1 tbsp sugar and 1/4 tsp each black peppercorns and hot-red-chili flakes. Add 2 heads of peeled garlic cloves. Boil 2 more min. Cool, then pour into a glass jar. Refrigerate for up to 2 weeks. Serve with sandwiches or add to salads.