In a large mixing bowl, stir together the flour, sugar, salt, sourdough discard, eggs, milk, vanilla, and avocado oil. Do not add the baking powder or baking soda yet; whisk just until no dry patches remain, then cover the bowl and refrigerate overnight.

The following morning, sift the baking powder and baking soda over the chilled batter. Whisk gently until the leaveners are fully mixed in.

The batter should look thick and show tiny bubbles. If it seems too dense to scoop, loosen it with 1 tablespoon of milk at a time.

Set the batter aside for at least 5 minutes so it becomes lively and bubbly. You can use it straight from the fridge.

For a same-day version, whisk the flour, sugar, salt, baking powder, and baking soda in a large bowl. Add the sourdough discard, eggs, milk, vanilla, and oil, then stir gently until smooth. Let the batter rest for 5 to 10 minutes.

Warm a large skillet or griddle over low heat and add about 1 tablespoon of oil, swirling to coat the bottom evenly.

Use a 1/3-cup scoop to pour the batter into the pan. Cook over low heat until the edges look set and bubbles pop on the surface, then flip. Continue cooking until both sides are deep golden. Serve warm with fresh berries, maple syrup, or strawberry puree.