Make the Remoulade: Stir vegan mayo, ketchup, Dijon, lemon juice, vinegar, capers, green onion, dill, parsley, grated garlic, Old Bay, smoked paprika, cayenne, and black pepper until smooth. Chill 15 to 30 minutes so it thickens and tastes extra put-together.
Make the Flax Egg: Mix ground flaxseed and water in a small bowl. Let it sit 5 to 10 minutes until gelled.
Dry the Hearts of Palm Like You Mean It: Chop hearts of palm, then wrap in paper towels or a clean towel and squeeze out as much liquid as possible. This is the difference between crisp cakes and soft cakes.
Get the “Crab” Texture: Optional but helpful, pulse the hearts of palm 3 to 6 quick pulses in a food processor to make flaky shreds. Do not turn it into paste.
Mix the Flavor Base: In a large bowl, combine hearts of palm, shallots, bell pepper, green onion, garlic, 6 tsp Old Bay, lemon zest, lemon juice, nori, parsley (if using), and black pepper.
Bind It Up: Add the flax egg and mix. Sprinkle in the oat flour and stir until evenly combined.
Add Crumbs and Rest: Fold in 1 1/4 cups crumbs. Let the mixture sit 5 minutes so the crumbs hydrate. If it feels too wet after resting, add crumbs 2 tbsp at a time until it holds together when pressed.
Shape with Confidence: Form into cakes and press firmly. Chill 20 to 30 minutes if you can, because it helps them hold their shape when flipping.
Coat for the Crunch: Mix the remaining 1/4 cup crumbs with the remaining 2 tsp Old Bay. Lightly press the coating onto the outside of each cake.
Pan-Fry to Golden: Heat a thin layer of oil in a skillet over medium heat. Cook 3 to 4 minutes per side until deep golden and crisp. Transfer to a rack or paper towels to rest for 2 minutes before serving.
Oven + Quick Sear Option: Coat cakes first, then place on a parchment-lined sheet pan. Lightly brush or spray the tops with oil. Bake at 425°F for 10 to 12 minutes. Flip, lightly oil the new top, bake 8 to 10 minutes more. Finish with a 45 to 60 second sear per side in a hot cast iron skillet with a little oil.
Serve It Up: Plate with a generous dollop of remoulade and a sprinkle of fresh herbs if you are feeling fancy.