Preheat oven to 350°F (175°C). Line the bottom of an 8-inch springform pan with parchment and lightly grease the sides.
In a mixing bowl, beat egg yolks with 1/2 cup (100 g) sugar and salt until paler and slightly thickened. Mix in lemon zest and vanilla.
Add almond flour and oil; mix until smooth.
In a clean bowl, whip egg whites to soft peaks. Add the remaining 2 tbsp (25 g) sugar and whip to glossy stiff peaks.
Fold one-third of the whipped whites into the batter, then gently fold in the rest until no streaks remain.
Pour batter into the prepared pan and smooth the top. Sprinkle sliced almonds evenly over the surface.
Bake 30–40 minutes, or until set and a toothpick comes out clean or with a few moist crumbs.
Cool 10–15 minutes, release the pan, and cool completely before slicing.