Slice each block of tempeh in half, making two equal-sized squares. Place tempeh pieces in pan and cover with water. Bring to a boil, reduce heat to medium-low, and simmer for 10 minutes. Alternately, place tempeh in steamer basket set over 2 inches water and steam for 10 minutes. Let tempeh cool and then slice into 2 inch chunks. Place tempeh in single layer into shallow container.

In bowl, whisk together 3 Tbsp olive oil, cider vinegar, 1 garlic clove, lemon zest, smoked paprika, cumin, and cayenne. Spread this mixture over tempeh and let marinade for at least 1 hour.

In small bowl, place parsley, oregano, 1 garlic, shallot, salt, and pepper. Stir in remaining 3 Tbsp olive oil and lemon juice.

Build medium-hot fire in charcoal grill, or heat gas grill to medium.

Onto metal skewers, thread tempeh chunks. Place skewers on grill and cook for 16 minutes, rotating every 4 minutes. Remove skewers from grill and carefully remove cooked tempeh from the skewers to serving plate. Serve topped with herb sauce.