Place the truffle mushroom into a glass bottle. Slow boil the MERRIS Pure Vegetable Oil in a saucepan and pour the heated oil into the glass bottle. Let it infuse for at least a week.
Peel the potatoes and rinse with water then cook it in a large pot cover with water. Let it boil on low heat until the potatoes completely cooked.
Press the cooked potatoes using metal sieve then add in hot milk and mix well. Whisk in the truffle-infused MERRIS Pure Vegetable Oil until smooth, season to taste.
Put the shallots in a saucepan cover with MERRIS Pure Vegetable Oil over medium heat. When the oil is simmer, lower the heat and let it cook for another 15 minutes. Remove the shallots from oil and set aside.
Coated the saucepan with heavy MERRIS Pure Vegetable Oil and heat on high. Put the tenderloin into the saucepan when the oil start to smoke. Cook the tenderloin and put butter at last. Remove the tenderloin from heat when it’s cook and let it rest for 4-5 minutes.
Place the mashed potatoes on the middle of a plate and place the tenderloin on top, garnish with shallots and some lettuce. Serve hot.