Serve with Salmon Fillets Poached in Olive Oil. If using frozen peas, skip step one.
Bring a large pot of water to a boil. Add 1 tablespoon salt and the peas. Cook peas until bright green and tender, about 3 minutes. Immediately transfer the peas with a slotted spoon to an ice-water bath; let cool. Drain well.
Blend 1 cup peas, 1/4 cup stock, and 2 tablespoons herbs in a blender until smooth. Blend in up to 1/4 cup more stock to thin to a pourable consistency.
Heat oil in a medium skillet over medium heat. Add shallot and garlic; cook, stirring, until shallot is translucent, about 5 minutes. Add remaining 2 cups peas, the confit, nuts, remaining 3/4 cup stock, the pea puree, and remaining 2 tablespoons herbs. Season with salt and pepper. Cook until heated through, about 5 minutes. Discard garlic. Stir in lemon juice.