In a food processor, combine garlic, onion, soy sauce, jalapeño peppers, apple cider vinegar, cumin, and pepper.
Process until well incorporated but still chunky.
Place the tempeh in a shallow dish or resealable plastic bag and pour the marinade over it.
Let marinate for a few hours.
When ready to cook, remove the tempeh from the marinade, reserving any leftover marinade.
If grilling, heat the barbecue to a medium-high flame.
Grill the tempeh for 5 to 7 minutes on each side, until nicely browned.
Alternatively, preheat the oven to 450°F (230°C, or gas mark 8).
Place the tempeh and reserved marinade in an ovenproof dish and bake, uncovered, for 10 to 12 minutes.
Serve with the reserved marinade.
Notes / Tips / Wine Advice:
Serving Tip:Serve with grilled vegetables or a fresh salad for a perfect barbecue meal.Wine Advice:A crisp, dry white wine like a Sauvignon Blanc complements the spice and depth of the marinade.