Mix together all of the broad bean topping ingredients in a bowl, add more seasoning if you see fit and leave to marinate at room temperature, covered, for about 1 hour if you have it, or at least 20 minutes.
Place all of the avocado topping ingredients in a bowl and lightly mix together until it's a little mashed but still chunky. You don't want the avocado to be too mushy! Taste for seasoning and add more salt/pepper/lemon if needed.
Grill the baguette slices either in a hot grill pan or frying pan, or under the grill in the oven until golden brown and crunchy. Drizzle generously with olive oil and rub each piece with the cut end of the garlic clove.
Top each piece of baguette toast with a little avocado mix, then pile a little scoop of the broad bean mix on top (best to do this on a chopping board as it can get a little messy). Transfer to a serving platter then sprinkle with a little extra flaky salt, some cracked black pepper, a drizzle of the tarragon‐y oil left over in the broad bean marinating bowl and a scattering of micro herbs or extra tarragon. Serve asap – with some white wine or champagne before dinner they are seriously perfect.