Lomo Saltado | Untried | Umami

Ingredients

• 1½ pounds sirloin tips, trimmed, cut into 3-inch pieces and sliced against the grain into ½-inch strips
• 1½ teaspoons ground cumin
• Kosher salt and ground black pepper
• 5 tablespoons soy sauce, divided
• 3 tablespoons grapeseed or other neutral oil, divided
• 1 large red onion, halved and cut into ½-inch half rings
• ¼ cup red wine vinegar
• 2 medium garlic cloves, minced
• 1 jalapeño chili, stemmed and sliced into thin rounds
• 1½ cups grape tomatoes, halved