Step 1In a bowl, soak the cashews in water, cover and set aside overnight at room temperature for the cashews to soften. The next day, strain the cashews, reserving the water. In a blender, puree the cashews with enough water to form a smooth sauce with the texture of heavy cream. Season with salt and lime juice to taste. This makes a generous cup of cream, which will keep, covered and refrigerated, up to 5 days.
Step 1In a nonreactive bowl, stir together the onion, lime juice and salt until the salt is dissolved and all of the onion is covered. Set the mixture aside to marinate for at least 20 minutes before assembling the tacos. The pickled onions will keep, 3 to 5 days, covered and refrigerated.
Step 1Brush the corn with a light coat of olive oil and sprinkle over salt and pepper to taste. Cook the corn over a grill or grill pan heated over medium-high heat until the corn is charred and tender on all sides, 6 to 8 minutes. Remove from heat and cut the kernels from the cobs. You should have about 1 cup corn kernels. Set aside.
Step 1Heat the oven to 400 degrees. In a bowl, toss the cauliflower florets with the olive oil, salt and pepper to taste, until evenly combined. Spread the cauliflower onto a rimmed baking sheet and roast until slightly charred and tender, about 15 minutes, depending on the size of the florets.
Step 1Heat a saute pan over medium-high heat until hot, and add the olive oil. Add the cauliflower and corn, stirring until warmed through. Remove from heat. Taste and season the mixture as desired with salt and lime juice.
Step 2To assemble the tacos, drizzle about 2 tablespoons cashew cream over each warmed tortilla. Spoon over about 1/2 cup of the cauliflower corn mixture. Top the mixture with a pinch of pickled onions, and garnish with cilantro leaves, roasted cashews and radish slices. Serve the tacos with lime wedges.