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Mushroom Meatball Subs with Caramelised Onion Mayonnaise

Ingredients

Subway Rolls (see recipe here)

    Mushroom Meatballs:

    • 1 tablespoon olive oil
    • 1 tablespoon butter
    • 1 small red onion (finely chopped) see note 1
    • 250g (9 oz) mushrooms (finely chopped) see note 2
    • 1 teaspoon minced garlic
    • 1 tablespoon Worcestershire sauce
    • 1 teaspoon salt
    • 1 teaspoon black pepper
    • 1 teaspoon paprika
    • 1 teaspoon oregano
    • 50g (1 cup) breadcrumbs
    • 50g (1¾ oz) mozzarella (grated)
    • 1 egg beaten

    Caramelised Onion Mayonnaise:

    • 1 tbsp olive oil
    • 2 tbsp butter
    • 2 large yellow onions
    • 1 tbsp Worcestershire sauce
    • mayonnaise

    Additional Ingredients:

    • salad accompaniments
    • salsa (optional)
    • mozzarella (optional)

    Instructions

    Caramelised Onion Mayonnaise:

    • Add the olive oil and butter to a pan and heat together.
    • Thickly slice the onions and add to the butter and oil.
    • Let them cook for five minutes, then add the Worcester sauce.
    • Continue to cool them on medium heat for around 20-30 minutes, stirring occasionally to make sure they aren't sticking. If they are cooking too quickly (starting to burn), turn the heat down.
    • When ready, spoon into a bowl, and allow them to cool completely.
    • When cooled, stir in as much mayonnaise as you like (I used around 1 cup / 250ml).

    Mushroom Meatballs:

    • Add the olive oil and butter to a pan.
    • When ready, add the chopped onions, and fry until soft.
    • Add the mushrooms, garlic, Worcester sauce, seasoning and spices. Stir until combined and cook for around five minutes.
    • Remove from the heat and allow to cool.
    • When ready, beat an egg in a large bowl.
    • Add the breadcrumbs and mushroom mixture, and give it a good stir to make sure it's well combined.
    • Using your hands, roll into balls, and place on a dish lined with baking paper.
    • Pop the mushroom meatballs in the freezer for 30 minutes to firm up.
    • When ready, fry in a little oil, or cook in your Airfryer (which is what I did). Handle them carefully, as they can be a little fragile.

    Assembly:

    • Slice the subway buns in half.
    • Apply a very thick spread of onion mayonnaise to one (or both) halves of the bread.
    • Use any kind of salad you want, and add it to one half of the bread. Top with the meatballs, along with a sprinkling of mozzarella and salsa (if using). Enjoy!

    Notes

    1. You can use either yellow/brown or red onions.
    2. I blitzed my mushrooms in a food processor as they feel more like "minced meat".
     
    Disclaimer:
    I have converted grams to cups/ounces/tablespoons using online converters. Although I have no reason to believe they are inaccurate, please be aware that I have not made the recipe with imperial measurements.
    In addition, many ingredients are different in Europe compared to North America. I do all I can to offer possible alternatives and to ensure the best possible outcomes for everyone. However, results cannot always be guaranteed if you have not used the same ingredients, measurements or methods as me.
    Lastly, I do everything I can to ensure that my recipes (and instructions) are accurate and easy to follow. However, I am human, and don't always get it right. If you notice anything strange, a mistake, or even a typo, please let me know in the comments.