In large skillet on high, heat 1 Tbsp (15 mL) olive oil. When oil is hot, add mushrooms and thyme sprigs and cook for about 5 minutes, shaking pan from time to time to toss, but otherwise keeping movement to a minimum. Once mushrooms are browned, add a pinch of salt and lemon juice, stir through, and tip out onto plate to rest.
Reduce heat to medium and, in the same pan, add remaining 1 tsp (5 mL) olive oil, leeks, and remaining salt. Cook leeks, being careful not to brown, for about 5 minutes, or until just soft. Tip mushrooms and thyme sprigs back into the pan, add honey, and combine with leeks. Remove pan from heat.
Toast 2 pieces of bread. When ready, add watercress to still-warm leek and mushroom mixture and mix through, just wilting watercress. Spoon onto toasted and plated bread and season with black pepper.
Enjoy!