Prep and measure everything first: zest and juice the lemon, chop the tarragon, mince the garlic, trim asparagus and rice the cauliflower if needed. Mise en place speeds cooking and ensures timing — especially because chicken will be hot off the grill when the veg needs to finish.

Make the marinade: in a bowl combine the lemon zest, lemon juice (about 2–3 tbsp from one medium lemon), 2 tbsp olive oil, half the chopped tarragon (2 tsp), 2 minced garlic cloves, 1 tsp kosher salt and a generous 1/2 tsp freshly cracked black pepper. Whisk to emulsify. Acid (lemon) brightens flavor and the oil helps transfer aroma and promote browning; the short acidity here seasons without over-tenderizing the thigh meat.

Marinate the chicken: place the 600 g chicken thighs in a shallow dish or resealable bag and pour the marinade over them, rubbing it into the meat. Cover and refrigerate for 20–60 minutes (up to 2 hours). Why: a short marinade lets citrus and tarragon flavor penetrate the surface without breaking down proteins too far — longer invites a papery texture from acid overexposure.

Bring chicken to near room temperature: remove the chicken from the fridge 15–20 minutes before cooking. This ensures more even cooking and a juicier result because the interior won’t be very cold when it hits the grill or pan.

Heat the grill or a heavy skillet: preheat a grill to medium-high (about 400–425°F / 200–220°C) or set a cast-iron skillet over medium-high heat and add 1 tbsp olive oil. Hot surface = Maillard reaction; searing creates that golden, caramelized crust and deep flavor.

Cook the chicken: remove chicken from marinade (reserve marinade). Pat the pieces lightly with paper towel to help them sear, season both sides with a pinch of salt and pepper, and grill or pan-sear 4–5 minutes per side for 150 g thighs (timing depends on thickness) until an instant-read thermometer reads 74°C / 165°F at the thickest point. Why: patting ensures a dry surface for browning; finishing temperature ensures safety and juiciness. Transfer to a plate and tent loosely with foil; let rest 5 minutes to redistribute juices.

While the chicken cooks, prepare the asparagus: toss the trimmed asparagus (320 g) with 1 tbsp olive oil, a pinch of salt and pepper. When chicken is resting, place asparagus on the grill or in the same skillet and char 2–4 minutes, turning once, until tender-crisp and lightly browned. Why: cooking asparagus after chicken lets you use the same hot pan or grill surface to capture fond and reduces equipment; short cooking keeps the spears bright and slightly crisp.

Warm the cauliflower rice: in a wide sauté pan over medium heat add the remaining 1 tbsp olive oil and 1 tsp butter. Add the remaining 2 minced garlic cloves and sauté 30–45 seconds until fragrant (don’t let it brown). Add the 480 g cauliflower rice, the reserved marinade (a tablespoon or two, strained if you prefer), the remaining chopped tarragon (2 tsp), 1/2 tsp salt and a few grinds of pepper. Sauté, stirring frequently, 4–6 minutes until just tender and most liquid has evaporated. Why: brief sauté keeps cauliflower from getting watery and lets the garlic-butter melt into the rice; adding reserved marinade layers the lemon-tarragon flavor into the bed rather than overpowering it.

Finish the cauliflower rice: remove pan from heat and stir in the remaining 3 tsp butter (or the remainder of the 1 tsp per person if using per-person amounts), which adds silkiness and mouthfeel. Taste and adjust salt and pepper. Why: finishing with cold butter (monter au beurre) gives a glossy finish and richer flavor without extra cooking time.

Assemble and finish with pea shoots: divide the warm cauliflower rice among 4 plates, arrange asparagus alongside, and top each plate with two chicken thighs (or the equivalent pieces totalling 150 g). Scatter 20 g pea shoots per plate over the warm rice — the residual heat will gently wilt them without losing their bright, peppery snap. Finish with a light drizzle of good olive oil, a grind of black pepper and, if you like, a quick microplane of lemon zest for brightness.

Optional pan sauce (chef's touch): while chicken rests, return the skillet to medium, add 2 tbsp water or white wine to deglaze, scrape up fond, add 1 tsp butter and a squeeze of lemon to make a glossy pan sauce. Spoon lightly over chicken for extra flavor.