Preheat the oven to 180 C.
Lay the chicken pieces on a baking tray and pat them dry with a paper towel. Season with salt and pepper. No oiling necessary.
Roast the chicken for 10 -15 mins or until cooked through. To test, pierce the thickest part of the chicken. If the juices run clear it’s cooked; if not, roast for a few more mins until the juices run clear. Alternatively, cook the chicken in a pan with a little oil until charred on the outside and cooked within.
Once cool enough to handle, shred the chicken into bite-sized pieces with your fingers. Set aside.
Toast the bread in a toaster, under the grill or in a pan with a little oil. Doesn’t matter which way you do it, you just want them to crisp up nicely. Cut into cubes.
Add the anchovies if using, some of the oil from the tin, black peppercorns and garlic cloves to a pestle and mortar. Pound until you have a paste and the black pepper has broken down into coarse nubbly bits.
Stir through the Dijon mustard, tahini, olive oil and lemon juice. Taste and adjust seasoning. If it appears too thick, thin out with some hot water. Set aside.
Add roughly chopped lettuce, chicken, avocado, bread, gherkins and pickled jalapeños to a large bowl. Pour over the dressing and toss just before serving. Taste and adjust seasoning.