In a small skillet, toast the fennel and coriander seeds for a couple of minutes until they're fragrant and slightly darker, about 2 minutes. Don't walk away from the pan! They'll burn! Remove from the pan and throw into a coffee/spice grinder. Grind to a fine powder.
Meanwhile, make the yogurt sauce: Mix the yogurt with the 1/2 cup finely chopped mint leaves and a generous pinch of salt. Chill in the fridge.
Throw the peas, edamame, ground spices, shallot, garlic, remaining whole mint leaves, olive oil, and salt into a food processor. Whizz it up and puree until smooth. It won't get completely smooth because of the edamame, but process until it is as smooth as possible.
Scrape into a big bowl and stir in the flour. The mixture will still be pretty soft. Not to worry!
Pour enough oil into a large cast iron skillet so that it's 1/4-inch deep. Heat over medium heat until shimmering. Meanwhile, with wet hands, shape the pea mixture into 12 small patties the size of a golf ball, and then gently drop into the oil. Fry until the bottoms are dark caramel brown, about 2 minutes, and then carefully flip over. Brown the other side, and then remove from the pan and drain on a paper towel-lined plate.
Serve warm in a pita bread pocket stuffed with the fresh veggies and a spoonful of the yogurt sauce.