Heat 4 teaspoons oil in a medium saucepan over medium-high heat. Add onion, garlic, 1/2 teaspoon salt, and a pinch of pepper. Cook, stirring, 3 minutes. Add stock, and bring to a boil.
Add peas, and return to a boil. Reduce heat, and simmer, stirring occasionally, until peas are tender and bright green, 2 to 3 minutes. Stir in spinach. Cover, and cook, stirring occasionally, until spinach has wilted, 2 to 3 minutes.
Working in 2 batches, puree pea mixture in a blender, filling no more than halfway and adding up to 2 tablespoons water to each batch to achieve desired consistency. Stir in 1 teaspoon lemon juice, 1/2 teaspoon salt, and 1/8 teaspoon pepper.
Divide the soup among 4 bowls. Toss greens with remaining teaspoon oil and 1/2 teaspoon lemon juice; season with salt and pepper. Divide salad among frico bowls. Float a frico bowl on top of each soup. Serve immediately.