In a small bowl, season the shallots with a pinch each of salt and sugar. Cover with vinegar and let sit for 10 minutes.
Meanwhile, bring a large pot of water to a boil over high heat. Shell the fava beans, then drop them in the water and cook for 1 minute. Drain and plunge them into an ice bath. Peel the favas and set aside. If you’re using edamame, boil for 1 minute, then plunge into the ice bath.
In a large bowl combine the endive, scallions, radishes, and favas. Whisk 1/3 cup oil into the vinegar mixture, pour it over the vegetables, and toss to coat. Taste and adjust the seasoning with salt, as needed. If you have small, tender basil leaves, add them to the bowl whole; otherwise, roughly chop the leaves, add them to the bowl, and toss to coat
In a small bowl, stir together the ricotta, mixed herbs, and lemon zest. Season with salt and pepper to taste.
Preheat the broiler to high. Arrange the bread on a sheet pan and drizzle with oil. Turn the slices over and drizzle with more oil. Transfer to the oven and broil for about 2 minutes, until golden, keeping an eye on them to prevent burning. Flip and broil the other side until golden, 1 to 2 minutes more. Transfer the bread to a serving board or platter
Spread each slice of bread with ricotta and mound the endive salad on top. Serve immediately.