Preheat the oven to 400 degrees. Toss the potatoes with 2 tsp salt and 1 T oil. Spread on a sheet pan and cook 30 min. Halfway through cooking, add the radishes, also tossed with salt and oil. In a deep skillet, melt the 4 T butter and add shallots. Cook until soft, about 5 min. Add the peas and stock. Simmer and cook 3-5 min. Reserve 1/4 cup stock. Drain the remainder from the peas. Add peas to food processor with salt. Process until smooth, adding reserve liquid if the mix is too stiff. In a large fry pan, heat the oil until just shimmering. Add the leeks and stir while cooking, careful not to burn the leeks. This should take about 5-10 min. Remove leeks and drain on paper towels. Warm 4 T of butter in a small pan. Cook until butter starts to brown but not burn. Place the salmon on a sheet pan and season with salt and pepper. Drizzle oil to lightly coat salmon. Cook for 12-15 min. Serve with a microgreen salad, lemon zest, and a drizzle of olive oil.