Keep the two larger Dover sole filets to one side; dice the smaller filets.
Place the diced filets in a blender, blend. Add egg white and blend again until smooth, add salt. Add heavy cream and blend until smooth.
Roll fish mousse into a cylinder and freeze.
Preheat water bath at 124°F (51°C).
Lay the 2 large filets down onto plastic wrap and dust skin side with Activa RM.
Place the frozen mousse on top of one filet, top with the second. Laying the head side of the top filet touching the tail side of the other.
Roll up tightly, removing any air. Set in the refrigerator for 2 hours.
Place Muscat grape juice, Verjus and low-acyl gellan gum together and blend with a Bamix immersion blender.
Heat mixture to 200°F (93.3°C) and hold for 3 minutes to activate the gum.
Remove from heat and pour into a mixing bowler ice to set.
Once set firm, place into a blender and blend until smooth, add xanthan gum to achieve correct consistency.
Whisk together grape juice, verjus, fructose and malic acid. Place into a vacuum pouch.
Blanch grapes in boiling water, refresh into iced water. Peel the skin.
Add the peeled grapes into the liquid in the pouch and seal on 100% vacuum.
When done, remove grapes from the pouch and slice finely.
Place minced shallot, Muscato, Verjus, and tarragon vinegar to a pot and reduce to a syrup.
Add heavy cream and reduce by half.
Add ice cold diced butter whisking one piece at a time.
Add finely minced chives.
Blanch tarragon leaves, then refresh in iced water. Squeeze gently to remove excess water.
Blend with oil in Vita-Prep until nearly smooth, about 40 seconds. Be sure not to blend too much or the color will be lost.
Add mixture to a small saucepan and heat until entire mixture is frying, around 1 minute. Quickly drain through chinois and cheesecloth into a container sat on ice.
Vacuum seal stuffed sole 100% vacuum and place in the water bath for 20 mins.
Remove from bath, season with Maldon salt. Cover with sliced grapes, overlapping to create a "fish scale" pattern.
Make a ring of fluid gel on the base of the plate. Place sauce in the center.
Cut a center piece of the cooked sole. Place in the center of the plate.
Cover the top of the fish tarragon oil.