Preheat the oven to 350ºF (177ºF) and line a standard cupcake pan with paper liners. In a large bowl, whisk together the flour, baking powder, and salt. Set aside.
Using a stand mixer fitted with the paddle attachment (or with a hand mixer and large bowl), mix together the sugar and lemon zest on low speed until fragrant and well combined, about 1 minute. Meanwhile, in a liquid measuring cup, combine the lemon juice with the milk and set aside.
Add the butter to the lemon-sugar mixture and cream it together on medium speed until well combined, about 2 minutes. It will look like wet sand at this point. Add the vegetable oil and beat until combined, light and creamy, about 3 minutes. Scrape down the bowl and paddle as needed.
With the mixer on low speed, add the eggs one at a time and mix until combined. Add the vanilla, then turn the mixer to medium speed and beat for one minute.
Turn the mixer off and add the flour mixture all at once. Mix on low speed until just combined, then slowly pour in the lemon milk mixture. Mix until just combined, about 30 seconds.
Using a spoon or scoop, add the batter to the cupcake liners and fill no more than 2/3 full. Bake for 14-18 minutes, until a toothpick inserted into the centers comes out clean or with a few moist crumbs. Cool in the pan for 5 minutes before removing and transferring the cupcakes to a wire rack to cool completely to room temperature.