You can swap out labneh for the goat cheese. I'd imagine fresh ricotta would work. Because ricotta can be a bit grainy, sometimes it's helpful to beat in a spoonful of cream. If peas aren't in season, fava or edamame beans would fill the bill, or top the tartines, nicely. (To go in a completely other direction, you could top the tartines with sliced tomatoes in place of the peas and radishes, and swap out mayonnaise or aioli for the goat cheese.) Feel free to use any fresh herbs that you like; chives, mint, basil, oregano, tarragon, chervil or thyme, and I think a mix is best. I went heavy on the basil and mint. Be sure to reserve extra herbs and shallots for sprinkling on top.