Preheat the oven to 350 degrees Fahrenheit and line an 8-inch springform pan with parchment paper.
In a large bowl, whisk together the eggs, avocado oil, pure maple syrup, zested lemon peel, lemon juice, and vanilla extract (wet ingredients).
In a separate bowl or measuring cup, stir together the flour, baking powder, and sea salt. Transfer the dry ingredients to the mixing bowl with the wet mixture and stir well until a thick, smooth batter forms.
Stir in the fresh blueberries and the poppy seeds gently using a rubber spatula until well-incorporated into the cake batter.
Pour batter into the prepared baking pan and spread it into an even layer. Cover the pan with aluminum foil. This prevents the top of the cake from browning too much.
Bake on the center rack of the preheated oven for 60 minutes. Remove the foil and bake for another 15 to 30 minutes, or until the cake tests clean (75-90 minutes total).
Insert a digital thermometer into the center of the cake to check its internal temperature. Cakes have the best texture when they are baked to 190 to 205 degrees Fahrenheit in the middle.
Allow the cake to cool completely before releasing it from the mold. Slice and serve with a scoop of vanilla ice cream and fresh fruit!