Easy Gan Bian Si Ji Dou (Sichuan Dry-Fried Green Beans)

Ingredients

• 1 teaspoon toasted whole Sichuan peppercorns (see notes)
• 3 tablespoons vegetable or canola oil, divided
• 6 whole dried small hot chiles (such as árbol)
• 4 medium cloves garlic, minced (about 4 teaspoons)
• 1 tablespoon minced fresh ginger
• 3 scallions, white and pale green parts only, thinly sliced
• 3 tablespoons finely minced whole or shredded Sichuan preserved mustard stems (see notes)
• 1 pound green beans, trimmed
• Kosher salt and freshly ground white or black pepper
• 2 teaspoons sugar