Heat an horno (similar to an outdoor bread oven) or home oven (with the rack positioned in the lower third of the oven) to approximately 500°F (260°C).
Pat the chicken dry with paper towels. Put the thyme, garlic, and bay leaves in the cavity and truss with kitchen twine.
Empty the salt into the sink (or a large basin or bucket if working outdoors). Pour 2 cups of water over the salt and, using your hands, toss to combine. Add more water as needed, a cup or two at a time, tossing until the mixture has the consistency of damp snow.
Make a 1-inch-deep bed of salt in a roasting pan and tamp it down. Place the chicken in the center. Stick the probe of a meat thermometer into the thickest part of the thigh. Cover the chicken completely with the remaining salt, tamping it down to make a salt crust so that it is completely encased.
Transfer the chicken to the oven and roast for 35 to 40 minutes; the internal temperature of the thigh should read 175°F (79°C). Spread newspapers on the counter next to the sink. Remove the pan from the oven, place on the newspaper, and let the chicken rest for 10 minutes. The internal temperature will rise to about 185°F (85°C).
Crack the salt crust with a rolling pin or mallet, lift off the pieces, and discard them. With a pastry brush, brush the remaining salt away from the chicken. Carefully pull off the skin from the breasts and legs. Slice off the chicken breasts from the bone and cut into 1/2-inch-thick slices. Slice the meat from the legs and thighs.
Arrange the meat on a warm platter and spoon the salsa over the chicken.