Gluten free breadless beef burger

What haven’t I done before? A breadless burger and served it like this. Ingredients (serves 2): 2 x Portobello mushrooms 1 x Vine tomato 1 x Ripe avocado 1 x Red onion 2 x Ice gem lettuce leaves 1 x Large gherkin sliced 1 x Egg 250g x Minced beef Rice flour Salt and pepper…