Add all spices to a bowl and mix together until evenly combined. Add cornmeal and potato starch to a large dish along with half of the spice mixture and mix together until well combined. Add jackfruit to a separate dish along with lemon juice and the remaining spice mixture. Mix until evenly coated.
Line a baking sheet with parchment paper or aluminum foil. Take each jackfruit segment and coat on all sides with the seasoned cornmeal mixture, tap it on the edge of the dish to knock any excess coating loose before placing on baking sheet. Continue this process until all of the jackfruit segments are coated and evenly distributed on the baking sheet. Use a silicone sauce brush to dab a light layer of grapeseed oil on each piece of jackfruit. Flip over and repeat the process until all of the jackfruit segments are evenly coated.
Bake for 15 minutes, then flip all the jackfruit segments with tongs and cook for an additional 15 minutes until both sides are golden brown and crispy. Serve with lemon wedges and vegan spicy mayo or vegan tartar sauce.