Veggie mushroom burger recipe
 An irresistible vegetarian mushroom burger filled with melty mozzarella and slathered in homemade tomato relish. This is designed to be a low cost recipe. 1 tbsp olive oil1 onion, finely dicedsalt and pepper 1 garlic clove, crushed 200g/7oz tinned tomatoes 1 tbsp white wine vinegar 1 tbsp olive oil 1 onion, finely diced salt and pepper 1 garlic clove, crushed 200g/7oz tinned tomatoes 1 tbsp white wine vinegar 25g/1oz butter 2 onions, finely sliced 25g/1oz butter 2 onions, finely sliced 4 large flat mushrooms, stalk trimmed so it doesn’t come above the edge of the mushroom 1 tbsp olive oil 1 ball mozzarella 4 burger buns, sliced in half 4 large flat mushrooms, stalk trimmed so it doesn’t come above the edge of the mushroom 1 tbsp olive oil 1 ball mozzarella 4 burger buns, sliced in half Method Preheat the oven to 180C/160C Fan/Gas 4.For the relish, heat a small frying pan over a medium heat and add the olive oil. Fry the onion and a pinch of salt in the oil for 4-5 minutes, or until the onion is soft. Add the garlic and cook for two minutes, then stir in the tomatoes and the vinegar. Gently simmer for five minutes, or until the mixture has thickened to a relish consistency. Taste and adjust the seasoning as necessary. Leave to cool.For the onions, heat a frying pan over a medium heat and melt the butter in the pan. Add the sliced onion and a pinch of salt. Turn down the heat and leave the onions, stirring now and again, to cook for 25-30 minutes, or until dark golden in colour and completely collapsed.For the rest of the burger, place the mushrooms with the stalk side facing up onto an oven tray, drizzle with the oil and season with salt and pepper. Bake in the oven for 10 minutes, or until beginning to soften. Meanwhile slice the mozzarella ball into four equal slices. After the mushrooms have cooked for 10 minutes, remove from the oven and place a slice of mozzarella into each of the mushrooms on top of the stalk. Put back into the oven for 5-7 minutes to melt the mozzarella.To assemble, lightly toast the cut side of the burger buns. Spread with a little relish and then place the mushrooms on top of the bottom burger bun. Divide the onions among the burgers and add any remaining relish on top. Finish by sandwiching each burger with the remaining halves. Preheat the oven to 180C/160C Fan/Gas 4. Preheat the oven to 180C/160C Fan/Gas 4. For the relish, heat a small frying pan over a medium heat and add the olive oil. Fry the onion and a pinch of salt in the oil for 4-5 minutes, or until the onion is soft. Add the garlic and cook for two minutes, then stir in the tomatoes and the vinegar. Gently simmer for five minutes, or until the mixture has thickened to a relish consistency. Taste and adjust the seasoning as necessary. Leave to cool. For the relish, heat a small frying pan over a medium heat and add the olive oil. Fry the onion and a pinch of salt in the oil for 4-5 minutes, or until the onion is soft. Add the garlic and cook for two minutes, then stir in the tomatoes and the vinegar. Gently simmer for five minutes, or until the mixture has thickened to a relish consistency. Taste and adjust the seasoning as necessary. Leave to cool. For the onions, heat a frying pan over a medium heat and melt the butter in the pan. Add the sliced onion and a pinch of salt. Turn down the heat and leave the onions, stirring now and again, to cook for 25-30 minutes, or until dark golden in colour and completely collapsed. For the onions, heat a frying pan over a medium heat and melt the butter in the pan. Add the sliced onion and a pinch of salt. Turn down the heat and leave the onions, stirring now and again, to cook for 25-30 minutes, or until dark golden in colour and completely collapsed. For the rest of the burger, place the mushrooms with the stalk side facing up onto an oven tray, drizzle with the oil and season with salt and pepper. Bake in the oven for 10 minutes, or until beginning to soften. Meanwhile slice the mozzarella ball into four equal slices. After the mushrooms have cooked for 10 minutes, remove from the oven and place a slice of mozzarella into each of the mushrooms on top of the stalk. Put back into the oven for 5-7 minutes to melt the mozzarella. For the rest of the burger, place the mushrooms with the stalk side facing up onto an oven tray, drizzle with the oil and season with salt and pepper. Bake in the oven for 10 minutes, or until beginning to soften. Meanwhile slice the mozzarella ball into four equal slices. After the mushrooms have cooked for 10 minutes, remove from the oven and place a slice of mozzarella into each of the mushrooms on top of the stalk. Put back into the oven for 5-7 minutes to melt the mozzarella. To assemble, lightly toast the cut side of the burger buns. Spread with a little relish and then place the mushrooms on top of the bottom burger bun. Divide the onions among the burgers and add any remaining relish on top. Finish by sandwiching each burger with the remaining halves. To assemble, lightly toast the cut side of the burger buns. Spread with a little relish and then place the mushrooms on top of the bottom burger bun. Divide the onions among the burgers and add any remaining relish on top. Finish by sandwiching each burger with the remaining halves. Recipe tips In November 2023 this recipe was costed at an average of £3.98 when checking prices at four UK supermarkets. This recipe is designed to be made in conjunction with a low-cost store-cupboard, for more details click here to see how our budget recipes were costed.