Panini Sayuran Alpukat

Bahan-bahan (4 porsi)

• 1 1/2 tablespoons butter or olive oil
• 1 minced shallot (onion or garlic works too)
• 8 ounces sliced baby portobello mushrooms
• 1 cup cherry or grape tomatoes
• 2 cups chopped kale, stems removed
• salt to taste
• 2 avocados
• 8 pieces thick, sturdy wheat bread
• melty white cheese like Provolone or Mozzarella, if you want