Combine the shoyu, Worcestershire sauce, agave, vinegar, garlic, salt and olive oil in a small mixing bowl. Whisk to combine.
Place the cauliflower head on a cutting board. Remove the outer leaves. Slice the cauliflower into 4-6 thick slices (each about 1 inch wide).
Place the cauliflower slices into a bag and pour the marinade over them. Allow to marinate at least 20 minutes.
Place the cauliflower slices on a baking sheet lined with a silpat mat or parchment paper. (Reserve the marinade.) Roast for 20 minutes. Baste with the reserved marinade every 10 minutes, flipping on each side.
Remove from the oven and top with the Lentil Olive Relish to serve.
Notes
Soy allergy? Use coconut aminos instead of soy sauce.Ditch the oil: Omit the oil or use vegetable broth.Spoiler Alert: Marinated Cauliflower Steaks with Lentil Olive Relish will stay fresh in an air-tight container in the refrigerator for a week.