Add the chicken, egg, almond flour, shallot, garlic, oregano, basil, salt and lemon juice to a large bowl. Use a wooden spoon or clean hands to mix until just combined.
Roll the mixture into tablespoon-size balls (it should make 14-15 meatballs). Wet your fingertips with a bit of water if you find the meatballs are sticking to your hands too much.
Heat a large skillet or dutch oven over medium-high heat and add 2 tablespoons of oil. When the oil is hot and shimmers, add the meatballs and sear until crisp and cooked through, about 8-10 minutes, turning them 2-3 times. The internal temperature should reach 165°F. Remove the pan from the heat while you prepare the tzatziki sauce.
To make the tzatziki, add all of the ingredients to the bowl of a food processor and pulse 10-15 times until combined and the cucumber breaks down into small bits. If you don’t have a food processor, finely chop or grate the cucumber and mix the ingredients in a bowl.
Serve the meatballs with a drizzle of tzatziki, crumbled feta, olives or parsley if desired. We love this with greek roasted vegetables, lemon orzo, asparagus or rice. It’s also great inside a wrap or pita!