This vegetarian dish is triple-grilled: The portobello mushroom steaks and thick tomato slices are each grilled, then they're stacked and covered with a quick, creamy béarnaise sauce and grilled one more time.
- In a bowl, whisk the shallot and vinegar with a generous pinch each of salt and pepper; let stand for 5 minutes. Whisk in the mayonnaise, tarragon and 1 1/2 tablespoons of water. Season the béarnaise sauce with salt and pepper.
- Light a grill and brush with oil. Brush the portobello caps with oil and season with salt and pepper. Grill over moderately high heat, turning once, until lightly charred, 6 minutes. Transfer to a plate. Brush the tomato with oil and season with salt and pepper. Grill, turning once, until lightly charred, 3 minutes total. Set the tomatoes on the portobellos.
- Spoon the béarnaise on the tomato slices. Transfer the stacks to the grill and close the grill. Cook over moderate heat until the sauce is just hot, 3 minutes. Transfer to plates, garnish with scallions and serve.
Make Ahead: This cheater's béarnaise can be refrigerated overnight.
Recipe Credit: Gabrielle Quiñónez Denton and Greg Denton
Image Credit: Christina Holmes