Preheat the oven to 400 degrees F.
On a baking sheet, toss the halved tomatoes with 1 tablespoon of the olive oil. Sprinkle with salt and pepper and transfer to the oven. Roast until the tomatoes are softened and lightly browned, about 30 minutes. Toss the kale and scallions in the remaining 1 tablespoon olive oil and season with salt and pepper. Once the tomatoes are roasted, scatter the kale and scallions around the tomatoes on the baking sheet, and bake until the kale begins to wilt, about 5 minutes. Remove from the oven and let cool.
While the tomatoes are roasting, make the hollandaise sauce: In a double boiler over medium-low heat, add the butter, half-and-half, lemon juice and zest and the 3 egg yolks. Cook, whisking, until thickened, about 10 minutes. Season with salt, pepper and a pinch of cayenne and maintain over low heat while you finish the recipe. If the sauce begins to thicken too much, whisk in 1 tablespoon of water.
Combine the vinegar and 6 cups water in a large saucepan and bring to a simmer over medium-low heat. One at a time, crack the 4 eggs into a small bowl and gently slide each one into the water. Simmer until the egg whites are set, 3 to 4 minutes. With a slotted spoon, remove the eggs to a paper towel-lined plate to drain.
Top each English muffin half with two tomato halves and some kale. Lay a poached egg on top and drizzle with hollandaise sauce. Serve immediately.