1/8 Teaspoon ground pepper Directions For the filet-o-tempeh sandwiches Step 1: To marinate the tempeh, slice the brick of tempeh in half and slice each half lengthwise so you have 4 thin fillets. Combine the 1/3 cup water, 1/3 cup vinegar, 2 tablespoons lemon juice, 2 teaspoons of the Old Bay, 1 teaspoon salt and 1 teaspoon pepper in a shallow dish. Submerge tempeh fillets in the marinade. Refrigerate for at least 30 minutes or upto 6 hours. Do not leave them longer than that or they may be too soft to handle without breaking. Step 2: When you are ready to fry the tempeh, add 4-6 cups vegetable oil to a heavy bottomed pot or deep fryer and heat to 350°F or as high as 360°F on a deep-frying thermometer.