Dipping sauces, such as ketchup, grainy mustard, pesto or red-pepper hummus, for serving
Set an oven rack in the highest position and heat the oven to 450 degrees Fahrenheit. On a baking sheet with a rim, place a cooling rack.
In a big skillet over medium-high heat, warm the oil. Add the onions and sauté them for approximately 5 minutes, turning often, until they are tender and golden. Turn off the heat and allow the food to cool in the skillet.
Cauliflower heads should have their cores and outer leaves removed. Trim away the majority of the remaining smaller stems after separating the heads into large florets. The florets should be processed in a food processor in two batches until very finely minced, nearly a paste, and then transferred to a large bowl. Decontaminate the food processor.
Place the cauliflower in the center of two layers of cheesecloth, then bundle the sides together. Place the cauliflower back in the bowl after pressing out as much liquid as you can over the sink. With your hands, combine the browned onion, almond meal, egg whites, and 2 teaspoons of salt until well incorporated and the dough stays together when squeezed. Scoop out equal tablespoon-sized portions, form each one into a ball, shape it into the shape of a squared-off tot, and arrange it on a baking sheet. The tots can be chilled overnight by covering them loosely with plastic wrap.
Rice cereal should be processed in the food processor in short bursts until it is very finely ground. In a larger dish, whisk the egg yolks with 1/4 cup water. Set out the prepared baking sheet, prepared tots, egg wash, ground cereal, and rack on your work area. Place the tots on the rack after coating them completely in the cereal and drizzling off any excess egg wash. Spray the cooking spray all over each tot, turning as necessary. (To prevent a mess, designate one hand for dipping and retrieving in the egg and the other for rolling in the cereal.) (Unsprayed breaded tots can be put on a baking sheet lined with parchment paper, frozen for about 2 hours, then transferred to a large freezer bag for up to 1 month. Coat with cooking spray before baking.)
On the prepared baking sheet, bake the tots for 15 to 20 minutes, or until they are heated throughout. Transfer to a serving platter after allowing it cool for a few minutes. As desired, serve with dipping sauces.