Vegan Grilled Portobello with Shallot Reduction

Score the top surface of each portobello cap with a shallow crosshatch pattern using a sharp knife. Slice the shallots, mince the garlic, strip the thyme leaves, chop the parsley, and zest the lemon. Whisk together the balsamic vinegar, red wine, 2 tbsp olive oil, tamari, Dijon mustard, thyme leaves, salt, and pepper in a shallow dish.

Place the portobello caps gill-side up in the marinade. Spoon the marinade repeatedly over the scored tops, then cover and set aside to marinate for 30–60 minutes at room temperature, turning once halfway through.

Warm the remaining 1 tbsp olive oil in a heavy skillet or sauté pan over medium heat. Add the sliced shallots and cook, stirring every 2–3 minutes, for 18–20 minutes until deeply golden, jammy, and caramelised. Add the garlic and cook for a further 2 minutes until fragrant. Deglaze with any remaining marinade and stir until the liquid is reduced and glossy, about 1 minute. Remove from heat and keep warm.

Heat a cast-iron grill pan or outdoor grill to high heat until smoking. Place the marinated portobello caps gill-side down and grill for 4–5 minutes until pronounced char marks form and the mushroom releases its liquid.

Flip the caps and grill scored-side down for 3–4 minutes until the tops are caramelised and the mushrooms have contracted and softened throughout.

Transfer the grilled caps to a warm plate. Spoon the caramelised shallot mixture generously into each gill cavity. Finish with chopped parsley and lemon zest before serving immediately.