30 ml olive oil - or 30 g butter
180 g banana shallots - about 3 medium-sized, finely chopped
4 garlic cloves - diced
60 g celery - 1 stalk, finely diced
250 g asparagus - trimmed and cut into 2.5 cm pieces (optional: reserve a few tips for garnish)
1500 ml vegetable or chicken stock
200 g starchy potatoes - e.g., Maris Piper or Yukon Gold, finely diced
150 g fresh peas - or frozen
200 g fresh spinach - left whole, no need to chop
10 g fresh dill - chopped (plus few springs for garnish)
Salt and black pepper - to taste
6 tbsp Greek yoghurt - to serve
1 Lemon - cut into wedges, to serve