1 pound lean beef sirloin, well trimmed, cut into 1-inch pieces
1/4 cup liquid aminos
1/4 cup fresh lime juice
1 tablespoon ground cumin
Freshly ground black pepper
1 red onion, cut into 16 wedges
16 small whole mushrooms
2 bell peppers cut into squares
Combine the first four ingredients in a bowl.
Season generously with pepper.
Cover and refrigerate overnight.
If you’re using wooden skewers, soak them for 20 minutes before you grill (you’ll need about 8 skewers).
Preheat the grill or broiler to medium-high heat.
Thread beef, onions, peppers, tomatoes and mushrooms onto skewers.
Grill or broil, turning occasionally, about 6 minutes for medium-rare.