¾ cup small-diced rainbow chard stems (from about ¾ bunch rainbow chard)
1 medium room-temperature grapefruit, skin removed and flesh cut into segments (¾ cup grapefruit segments)
3 teaspoons sherry vinegar, divided
½ cup (about 4 ounces) bacon lardons
2 cups torn country-style bread
Pinch kosher salt, plus more to taste
½ cup toasted hazelnuts, roughly chopped
1½ teaspoons finely chopped rosemary
Canola oil, if needed
3 packed cups torn curly kale leaves
6 packed cups torn rainbow chard leaves (from about 1 bunch rainbow chard)
Directions
In a medium bowl, toss together the diced rainbow chard stems, grapefruit and 1 teaspoon of the sherry vinegar. Set aside, occasionally stirring to mix.
In a large skillet over medium-high heat, add the bacon and sauté, stirring occasionally, until the fat renders and the bacon becomes crisp, 5 to 7 minutes. Using a slotted spoon, transfer the bacon to a large mixing bowl and set aside. Pour the fat into a separate small bowl, leaving about 2½ teaspoons of fat in the skillet. Reserve the rest of the fat for later.
Return the skillet to medium-high heat, add the torn bread and season with a pinch of salt. Sauté, stirring occasionally, until toasted and crunchy, 5 to 7 minutes. Add the hazelnuts and rosemary, stirring to combine, then add to the bowl of bacon. Toss to mix and set aside.
Add 1 teaspoon of the reserved bacon fat (or canola oil if you're out of bacon fat) to the skillet and return to high heat. When the pan is hot, add the kale and season with a pinch of salt. Sauté until bright green and slightly charred, occasionally flipping the greens with a pair of tongs to stir, 2 to 3 minutes. Add the chard leaves and cook until slightly wilted, 1 to 2 more minutes.
Pour the bacon mixture into the pan and cook until the salad is warmed throughout, 20 to 30 seconds more. Remove from the heat and drizzle the remaining 2 teaspoons of sherry vinegar into the skillet, stirring to mix. Taste and adjust the seasoning with salt. Serve immediately, spooning over some of the pickled chard stem and grapefruit mixture.