1. Thinly slice scallions, separating darker green parts for garnish.
2. In a skillet over medium heat, melt butter. Add light green and white parts of scallion and sauté until wilted, 2 minutes. Add sorrel leaves, salt and pepper. Cook, stirring, until sorrel wilts and starts to break down, turning olive-green in color, about 3 minutes. Stir in cream and let simmer for 1 minute to thicken a bit.
3. Carefully crack eggs into skillet; they should fit in one layer. Lower heat to medium-low and sprinkle eggs with salt and pepper. Cover pan and let cook for 2 minutes, then turn off heat and let eggs rest, covered, until done to taste, about another 30 seconds for very runny yolks (the whites should cook through).
4. Carefully scoop eggs and sorrel sauce into two bowls. Season with chili and flaky salt; garnish with scallion greens. Serve with toast.