An avocado sandwich showcases creamy mashed or sliced avocado as the star, spread generously on toasted bread for a rich, buttery base. Common additions include fresh tomatoes, cucumber slices, red onion, arugula, sprouts, feta or herbs, and seasonings like lemon juice, garlic, salt, and pepper. Variations feature spicy mayo, pickled onions, or veggies like carrots for extra crunch and tang.