How to Make It
Preheat the oven to 450°. Heat a 9-inch cast-iron skillet in the oven for at least 10 minutes.
In a large nonstick skillet, cook the bacon over moderately low heat, stirring frequently, until crisp and the fat has rendered, 7 to 8 minutes. Transfer the bacon to paper towels to drain. Scrape the bacon fat into a small measuring cup and stir in enough canola oil to make 5 tablespoons total.
In a large bowl, whisk the cornmeal with the salt, baking powder, baking soda and bacon. In a medium bowl, whisk the buttermilk with the eggs and bacon oil. Stir the wet ingredients into the cornmeal mixture.
Grease the hot cast-iron skillet with canola oil. Add the corn bread batter, spreading it evenly. Bake for about 20 minutes, until the corn bread is golden and a toothpick inserted in the center comes out clean. Transfer to a rack and let cool slightly, then unmold the corn bread and let cool completely. Cut half of the corn bread into 1/2-inch cubes; reserve the rest for another use.
In a small bowl, whisk together all of the ingredients and season with salt. Let stand at room temperature for 1 hour.
In a large pot, heat the canola oil. Add the bacon and cook over moderate heat for 3 minutes, stirring occasionally. Add the peas, stock, thyme and bay leaf and bring to a boil. Cover and cook over low heat until the peas are tender, about 45 minutes. Drain the peas and discard the thyme sprigs and bay leaf; reserve the cooking liquid for another use.
Transfer the peas to a large bowl and stir in the butter, lemon juice and hot sauce. Season with some of the vinaigrette. Add the watercress, season with salt and white pepper and toss. Transfer the salad to plates and garnish with the corn bread croutons. Serve the extra vinaigrette on the side.