Brush the zucchini, yellow squash and avocados with the olive oil and season lightly with salt and pepper. Grill the vegetables until tender and charred in spots, turning once. Meanwhile, grill the burgers according to package instructions, then cut into bite-sized pieces.
To assemble, divide the chopped cabbage evenly among 4 bowls. Top with the burgers and grilled vegetables. Place a small pile of pickled red onions in each bowl and sprinkle everything spice over everything. Serve at once, with lemon wedges.
Pickled Red Onions:
Makes about 1 cup / Takes less than 10 minutes
Combine the onions, vinegar, and salt in a small bowl and stir until the salt is dissolved.
Cover tightly and refrigerate overnight. The pickled onions keep, tightly covered, up to 1 week in the refrigerator.
Makes about ⅓ cup / Takes less than 10 minutes
Combine all ingredients in a small bowl.
Stir everything together until well combined. The everything spice can be kept in an airtight container at room temperature for up to 1 month.