Preheat oven to 400 degrees F (200 degrees C).

Add grated zucchini to a food processor, then transfer to a strainer. Add salt and let sit for 10 minutes.

In the meantime, add red onion and Brussels sprouts to a food processor and pulse until finely chopped.

Set chopped onions and Brussels sprouts aside. Add Great Northern beans to the food processor and pulse until nearly pureed.

Squeeze out all water from the zucchini and add to a large bowl.

Add the chopped onion, Brussels sprouts, pureed beans, feta cheese, flaxseed meal, chia seeds, almond meal, and sunflower kernels to the bowl.

Add smoked paprika and ground black pepper. Stir until well combined. Refrigerate for 1 hour or longer.

Form the mixture into 6 to 8 patties.

Place patties on a wax-lined baking sheet and bake for 12 minutes.

Remove the tray, gently flip the patties, and bake for another 8 to 10 minutes or until cooked to your liking.

Add avocado, garlic, sriracha, smoked paprika, lemon juice, vanilla almond milk, red bell pepper, and fresh basil leaves to a food processor. Blend until smooth and creamy.

Assemble the veggie burgers using your preferred choice of buns. Top patties with sriracha avocado sauce and your choice of toppings such as red bell peppers, fresh spinach, cheese, onions, and sliced avocados.