• In a fine-mesh strainer, rinse the quinoa.
• Finely chop the tomatoes.
• Juice half the lemon (the juice will be divided between the quinoa and the white bean mash); cut half into wedges for garnish.

In a small sauce pot, combine the quinoa, tomatoes, and 1 cup lightly salted water. Bring to a boil, reduce to a simmer, cover, and cook until the quinoa is tender and the water is absorbed, 15 to 20 minutes.
Remove from the heat. Add the spinach, 2 teaspoons lemon juice, and 1 to 2 teaspoons oil and stir to combine; season to taste with salt and pepper. Cover and let stand while you prepare the rest of the meal.

• Finely chop, press, or grate enough garlic to measure 1 teaspoon.
• Strip the rosemary leaves from the stems; finely chop the leaves.
• Rinse the white beans.

In a medium frying pan over medium heat, warm 2 tablespoons oil until hot but not smoking. Stir in the garlic and rosemary and cook until fragrant, about 30 seconds. Stir in the white beans and 1 tablespoon white wine, if using, and cook until the beans are warmed through, about 1 minute. Transfer the beans to a medium bowl, add 1 teaspoon lemon juice, and mash with a fork or the bottom of a cup. Season to taste with salt and pepper. Cover to keep warm. Wipe out the pan.

• Wipe the top of the portobello mushrooms with a damp paper towel to remove any dirt. Remove the stems and, using a spoon, gently scrape the black gills from the undersides of the caps.
• Brush the mushrooms all over with oil and season generously with salt and pepper.

In the same pan used for the white beans, warm 1 tablespoon oil over medium-high heat until hot but not smoking. Add the mushrooms, cap sides down, and cook, turning once, until browned and just starting to soften, 5 to 7 minutes.
While the mushrooms cook, chop the hazelnuts.

• Coarsely chop the hazelnuts.

Spread the white bean mash onto individual plates. Top each with a mushroom, cap side down, and fill with the quinoa mixture. Garnish with the hazelnuts and serve the lemon wedges and any remaining quinoa on the side.