For fish fillet and lime gremolata on crostini, preheat the grill function on the oven.
Cut the baguette diagonally into thin slices, drizzle with a little olive oil and roast on both sides in the oven until crispy. Then turn off the oven.
Season the fish fillet with the juice of half a lime, salt and pepper. Heat a pan over medium heat, add a little olive oil and slowly fry the fish fillets on one side until they are just slightly glazed on the surface. Set aside in the oven while still warm.
In the meantime, wash and dry the spinach. Slice shallots into thin wedges and sauté with the spinach in a little olive oil, seasoning with salt, pepper and nutmeg. Set aside in a bowl.
For the lime gremolata, while the pan is still hot, lightly toast the almond slivers in a little olive oil, remove pan from heat. Finely chop the parsley, chili and garlic.
Grate the zest of 2 limes, then thinly peel the limes all around with a small knife, cut out the fillets and add to the pan with the grated zest and the remaining ingredients. Stir well, season with salt, pepper and the juice of the remaining lime.
Top crostinis with some spinach leaves, place a small piece of fish fillet on each, garnish generously with the gremolata and serve the fish fillet and lime gremolata on crostini immediately.