Step 1

Purée basil, parsley, tarragon, mayonnaise, sour cream, lemon zest, 2 Tbsp. lemon juice, and 2 Tbsp. oil in a blender until very smooth and pale green. Transfer dressing to a medium bowl and add tuna. Using a fork, break up tuna and incorporate into dressing. Mix in celery, shallot, and garlic; season with salt and lots of pepper.

Step 2

Toss chopped mixed herbs with remaining 1 tsp. lemon juice in a small bowl. Drizzle with a little oil, season with salt and pepper, and toss again.

Step 3

Build sandwiches with English muffins, tuna salad (you may have a bit extra), and herb salad.