Start the lentils: Set a medium saucepan over medium heat. Set a large nonstick or well-seasoned skillet near the stove for the fritters.

Add 1 tablespoon of the olive oil and half of the scallion whites to the saucepan. Cook for 1 to 2 minutes, stirring often, until the scallions soften.

Pour the crushed tomatoes into the saucepan. Add 1/2 teaspoon of the salt and 1/2 cup water, and bring the sauce to a gentle simmer.

Add the drained lentils to the saucepan and stir well. Lower the heat to medium-low and let the lentils simmer for 10 to 12 minutes, stirring once or twice, until they are hot and the sauce thickens slightly.

Mix the fritters: Put the asparagus, the remaining scallion whites, half of the dill, the ricotta, 1/3 cup of the Parmesan, the lemon zest, the eggs, the flour, the remaining 1 teaspoon salt, and the baking powder into a large bowl.

Stir the mixture with a spoon until the flour disappears and a thick batter forms. If the batter looks loose, let it stand for 5 minutes so the flour can absorb some moisture.

Set a large plate or sheet pan near the stove for the cooked fritters. Add 2 tablespoons of the olive oil to the skillet and heat it over medium heat until the oil looks glossy.

Scoop scant 1/4-cup portions of batter into the skillet, making 4 fritters at a time. Gently flatten each one to about 1/2 inch thick with the back of the scoop or a spoon.

Cook the fritters on the first side for 3 to 4 minutes, until the edges look set and the bottoms are deep golden brown.

Turn the fritters with a thin spatula. Cook them on the second side for 3 to 4 minutes, until the centers feel springy and the asparagus is tender.

Transfer the cooked fritters to the plate or sheet pan. Add another 1 tablespoon of olive oil to the skillet if the pan looks dry.

Cook the remaining batter the same way, again using scant 1/4-cup portions. Lower the heat a little if the outsides brown too fast before the centers cook through.