Heat a large high-sided pot over medium-heat and add the olive oil. When the oil is shimmering, add the leeks, a pinch of salt, and cook until softened, about 5 - 6 minutes.
Add the chili flakes, garlic, tarragon, and cook for 30 seconds, then stir in the flour and coat the leeks well.
Add the potatoes and stock, then bring to a simmer and cook until the potatoes are just fork tender.
Season the fish well with salt.
To your pot of goodness, add the cream, asparagus, peas, lemon zest, your fish, then bring to a simmer and cook until the fish is opaque and just cooked through, about 3 - 4 minutes.
Taste the chowder and season to taste with salt.
Plate up, top with cracked black pepper, chives, dill, a squeeze of lemon, and serve.
