For the burger: Mix the chorizo and Italian sausage together in a bowl. Make 4 equal-size portions and flatten to about 4 inches in diameter.
Heat a large skillet over medium-high heat. Add the patties and 1/4 cup of water, cover and cook for 5 to 6 minutes on each side until the water is evaporated. Sear uncovered until slightly crispy for about 2 minutes, then remove to rest.
Butter and toast the rolls.
For the avocado-tomato mayo: Mix the tomato, mayo, lemon juice, cilantro, garlic, scallion and avocado in a bowl until well incorporated. Season to taste.
Spread equal amounts of the avocado-tomato mayo on both sides of the toasted rolls, then top the bottom rolls with a potato crisp, a patty, an egg and then the top rolls.